Devices for reduced overhead paging

ABSTRACT

A method for reduced overhead paging by an access point is described. The method includes assigning at least one paging identifier to at least one station. The method also includes partitioning a paging identifier space into paging identifier sets. The method further includes generating a paging message based on at least one of the paging identifier sets and the at least one paging identifier. The method additionally includes sending the paging message.

RELATED APPLICATIONS

This application is related to and claims priority from U.S. ProvisionalPatent Application Ser. No. 61/523,033 filed Aug. 12, 2011, for “SYSTEMSAND METHODS FOR LOW OVERHEAD PAGING,” U.S. Provisional PatentApplication Ser. No. 61/552,444, filed Oct. 27, 2011, for “Systems andmethods for low overhead paging,” U.S. Provisional Patent ApplicationSer. No. 61/552,661 filed Oct. 28, 2011, for “SYSTEMS AND METHODS FORLOW OVERHEAD PAGING,” U.S. Provisional Patent Application Ser. No.61/591,493, filed Jan. 27, 2012, for “SYSTEMS AND METHODS FOR LOWOVERHEAD PAGING,” and U.S. Provisional Patent Application Ser. No.61/598,200, filed Feb. 13, 2012, for “SYSTEMS AND METHODS FOR LOWOVERHEAD PAGING.”

TECHNICAL FIELD

The present disclosure relates generally to electronic devices. Morespecifically, the present disclosure relates to devices for reducedoverhead paging.

BACKGROUND

In the last several decades, the use of electronic devices has becomecommon. In particular, advances in electronic technology have reducedthe cost of increasingly complex and useful electronic devices. Costreduction and consumer demand have proliferated the use of electronicdevices such that they are practically ubiquitous in modern society. Asthe use of electronic devices has expanded, so has the demand for newand improved features of electronic devices. More specifically,electronic devices that perform functions faster, more efficiently orwith higher quality are often sought after.

Some electronic devices (e.g., cellular phones, smart phones, computers,etc.) communicate with other electronic devices. These electronicdevices may be referred to as communication devices. These electronicdevices may generate and transmit data to other electronic devices. Forexample, a laptop computer may format data into packets and wirelesslytransmit the packets to an access point.

In many telecommunication systems, communications networks are used toexchange messages among several interacting spatially separated devices.Networks may be classified according to geographic scope, which couldbe, for example, a metropolitan area, a local area, or a personal area.Such networks would be designated respectively as a wide area network(WAN), metropolitan area network (MAN), local area network (LAN),wireless local area network (WLAN), or personal area network (PAN).Networks also differ according to the switching/routing technique usedto interconnect the various network nodes and devices (e.g. circuitswitching vs. packet switching), the type of physical media employed fortransmission (e.g. wired vs. wireless), and the set of communicationprotocols used (e.g. Internet protocol suite, SONET (Synchronous OpticalNetworking), Ethernet, etc.).

Wireless networks are often preferred when the network elements aremobile and thus have dynamic connectivity needs, or if the networkarchitecture is formed in an ad hoc, rather than fixed, topology.Wireless networks employ intangible physical media in an unguidedpropagation mode using electromagnetic waves in the radio, microwave,infra-red, optical, etc., frequency bands. Wireless networksadvantageously facilitate user mobility and rapid field deployment whencompared to fixed wired networks.

Some aspects of network control may require overhead signaling. However,known approaches to network control may be inefficient, often requiringexcess amounts of bandwidth, time and/or power to operate. As can beobserved from this discussion, systems and methods that improve networkcontrol efficiency may be beneficial.

SUMMARY

A method for reduced overhead paging by an access point is described.The method includes assigning at least one paging identifier to at leastone station. The method also includes partitioning a paging identifierspace into paging identifier sets. The method further includesgenerating a paging message based on at least one of the pagingidentifier sets and the at least one paging identifier. The methodadditionally includes sending the paging message.

At least one of the paging identifier sets may include a continuousinterval of multiple paging identifiers. The paging message may includean explicit identifier that identifies at least one of the pagingidentifier sets. At least one paging identifier set may be implicitlyidentified by a sequence number associated with the paging message.

At least one paging identifier set may be implicitly identified by atime at which the paging message is sent. The at least one pagingidentifier may be addressed relative to at least one of the pagingidentifier sets. A relative position of the at least one pagingidentifier may be assigned through a specific management message. Arelative position in the at least one paging identifier set mayrepresent an offset corresponding to the at least one paging identifier.

Absolute addressing may be utilized to identify the at least one pagingidentifier in at least one paging identifier set. Absolute addressingmay include a local address, a global address or a paging identifier.

No explicit indication may be used to address the at least one pagingidentifier in at least one paging identifier set. All stationscorresponding to the at least one paging identifier set may beimplicitly paged when the paging message indicates the at least onepaging identifier set. One bit may indicate whether all stationscorresponding to the at least one paging identifier set are paged. Allstations corresponding to a given range of paging identifiers may bepaged.

The access point may be an access point in accordance with Institute ofElectrical and Electronics Engineers (IEEE) 802.11 specifications.

The method may include compressing the paging message to obtain acompressed paging message. Sending the paging message may includetransmitting the compressed paging message to the at least one station.

The method may include scheduling a transmission by one or more stationsof the at least one station. The method may include generating the atleast one paging message based on the scheduling of the one or morestations of the at least one station.

The paging message may include a bitmap element. The method may includedefining at least one sub-bitmap element. The method may also includeincluding a variable length bitmap into the at least one sub-bitmapelement.

The method may include compressing the bitmap to obtain running lengthsequences based at least in part on the bitmap. The method may includeassigning a different association identifier. The method may includeassigning an association identifier to the at least one station.

The paging message may include one or more of the group consisting of anequipment identifier field, a length field, a control field, an offsetfield and a bitmap. The paging message may include an offset, a lengthand/or a bitmap.

A method for reduced overhead paging by a station is also described. Themethod includes determining at least one paging identifier assigned tothe station. The method also includes determining at least one pagingidentifier set corresponding to the at least one paging identifier. Themethod further includes determining whether a paging message correspondsto the station based on the at least one paging identifier set. Themethod additionally includes determining whether the station is paged ifthe paging message corresponds to the station.

The method may include setting the station to an awake state if thestation is paged. Determining whether the paging message corresponds tothe station may be based on whether an explicit identifier identifiesthe at least one paging identifier set corresponding to the at least onepaging identifier. Determining whether the paging message corresponds tothe station may be based on whether the at least one paging identifierset is implicitly identified by a sequence number associated with thepaging message. Determining whether the paging message corresponds tothe station may be based on whether the at least one paging identifierset is implicitly identified by a time at which the paging message issent.

The station may be paged if the at least one paging identifier isaddressed relative to at the least one paging identifier set. A relativeposition of the at least one paging identifier may be assigned through aspecific management message. A relative position in the at least onepaging identifier set may represent an offset corresponding to the atleast one paging identifier. The station may be paged if absoluteaddressing identifies the at least one paging identifier in the at leastone paging identifier set.

Absolute addressing may include a local address, a global address or apaging identifier. No explicit indication may be used to address the atleast one paging identifier in at least one paging identifier set. Thestation may be paged implicitly if the at least one paging identifierset corresponds to the station. The paging message may include one bitthat indicates whether the station corresponding to the at least onepaging identifier set is paged.

The station may be paged if the at least one paging identifier is withina given range of paging identifiers. The station may be a station inaccordance with Institute of Electrical and Electronics Engineers (IEEE)802.11 specifications.

The method may include receiving at least one compressed paging messagefrom an access point. The method may also include reconstructing thepaging message from the compressed paging message.

The paging message may be associated with the at least one pagingidentifier of the at least one paging identifier set. Each of the atleast one paging identifier may be associated with at least one stationof a set of stations.

The method may include selecting a first paging identifier from aplurality of paging identifiers that are included in the paging message.The method may also include transmitting a request to an access pointindicating selection of the first paging identifier.

A method for wireless communication by a station is also described. Themethod includes preparing a polling message comprising a token number.The token number corresponds to the token number in one or more pagingmessages and is configured to indicate a correspondence between thepolling message and the one or more paging messages. The method alsoincludes transmitting the polling message to an access point.

The paging message may include an equipment identifier field, a lengthfield, a control field, an offset field and/or a bitmap. The station mayhave an association identifier. The paging message may include offset, alength or a bitmap.

A method for wireless communication by an access point is alsodescribed. The method includes determining a transmission schedule for afirst plurality of stations. The first plurality of stations may beselected from a second plurality of stations. The method also includesdetermining a duration of a reserved time interval that is reserved fortransmission.

The paging message may be associated with at least one paging identifierof a plurality of paging identifiers. Each of the plurality of pagingidentifiers may be associated with at least one station of the firstplurality of stations.

The method may include transmitting the paging message to at least oneof the second plurality of stations. The method may also includecommunicating the duration of the reserved time interval to at least oneof the second plurality of stations.

Another method for wireless communication by an access point is alsodescribed. The method includes determining a reserved time interval. Themethod also includes setting the reserved time interval for at least onepaged station by setting a network allocation vector.

Another method for wireless communication by an access point is alsodescribed. The method includes preparing a plurality of paging messages.Each of the plurality of paging messages is associated with at least onepaging identifier of a plurality of paging identifiers and comprises atoken number. Each of the plurality of paging identifiers is associatedwith at least one station of a set of stations. The method also includestransmitting at least one paging message to the at least one station.The method further includes receiving a polling message from the atleast one station. The polling message includes the token number. Thetoken number corresponds to the token number in one or more pagingmessages and is configured to indicate a correspondence between thepolling message and the one or more paging messages. The methodadditionally includes associating the one or more paging messages withthe polling message.

Another method for wireless communication by a station is alsodescribed. The method includes determining a schedule for transmitting apolling message to an access point. The schedule is based on at leastone paging identifier.

The schedule may include a time at which the station transmits thepolling message. The schedule may include a time at which the stationbegins contention for a communication channel to transmit the pollingmessage. The schedule may include a counter, which the station may countdown before transmission of a transmit polling message while acommunication channel is idle. The schedule may be based on a hashfunction of the station first paging identifier.

The method may include obtaining information relative to a time intervalreserved for transmission by a plurality of stations selected from a setof stations. The method may include performing a determination as towhether to send a polling message to the access point. The determinationmay be based on the first paging identifier and the information relativeto the reserved time interval.

Another method for wireless communication by a station is alsodescribed. The method includes selecting a first paging identifier froma plurality of paging identifiers based on a schedule by which an accesspoint transmits paging messages comprising the first paging identifier.The method also includes transmitting a request to the access pointindicating selection of the first paging identifier.

The schedule may be predefined by the access point. The schedule may bedefined by the access point based on the receipt of one or morerequests. The request may include a frame comprising the first pagingidentifier. The frame may further include an equipment identifier, alength field, a control field, and timing information regarding timeswhen receipt of paging messages is requested.

The method may include receiving a response to the request, the responseindicating assignment of the first paging identifier. The response mayinclude a frame comprising the first paging identifier. The frame mayalso include an equipment identifier, a length field, a control field,and timing information regarding times paging messages associated withthe first paging identifier are transmitted by the transmitting device.

The method may include receiving at least one compressed paging messagefrom the access point. The method may include reconstructing the pagingmessage based at least in part on the compressed paging message.

Another method for wireless communication by a station is alsodescribed. The method includes obtaining information relative to a timeinterval reserved for transmission by a plurality of stations selectedfrom a second plurality of stations. The method also includes performinga determination as to whether to send a polling message to an accesspoint. The determination is based on the first paging identifier and theinformation relative to the reserved time interval.

The determination may include determining whether the station isscheduled for transmission to the access point. If the determination isto send a polling message, the method may further include transmitting amessage to the access point during the reserved time interval. If thedetermination is not to send a polling message, the method may furtherinclude waiting until expiration of the reserved time interval. Uponexpiration of the reserved time interval, the method may further includetransmitting a message to the access point.

Transmitting the message may be based on the result of a contention withone or more devices. Transmitting the message may be based on the resultof a contention with one or more devices.

A contention may include assigning to a device a time slot to access themedium. A contention may include assigning to a device a value to beused for random back-off. A contention may include assigning to a devicea deterministic back-off value.

The schedule may indicate an order. The order may be randomized. Thestation may be paged if the at least one paging identifier is within agiven range of paging identifiers.

An access point for reduced overhead paging is also described. Theaccess point includes a processor and instructions stored in memory thatis in electronic communication with the processor. The access pointassigns at least one paging identifier to at least one station. Theaccess point also partitions a paging identifier space into pagingidentifier sets. The access point further generates a paging messagebased on at least one of the paging identifier sets and the at least onepaging identifier. The access point additionally sends the pagingmessage.

A station for reduced overhead paging is also described. The stationincludes a processor and instructions stored in memory that is inelectronic communication with the processor. The station determines atleast one paging identifier assigned to the station. The station alsodetermines at least one paging identifier set corresponding to the atleast one paging identifier. The station further determines whether apaging message corresponds to the station based on the at least onepaging identifier set. The station additionally determines whether thestation is paged if the paging message corresponds to the station.

A station configured for wireless communication is described. Thestation includes a processor and instructions stored in memory that isin electronic communication with the processor. The station prepares apolling message including a token number. The token number correspondsto the token number in one or more paging messages and is configured toindicate a correspondence between the polling message and the one ormore paging messages. The station transmits the polling message to anaccess point.

An access point configured for wireless communication is described. Theaccess point includes a processor and instructions stored in memory thatis in electronic communication with the processor. The access pointdetermines a transmission schedule for a first plurality of stations.The first plurality of stations is selected from a second plurality ofstations. The access point also determines a duration of a reserved timeinterval that is reserved for transmission.

Another access point configured for wireless communication is alsodescribed. The access point includes a processor and instructions storedin memory that is in electronic communication with the processor. Theaccess point determines a reserved time interval. The access point alsosets the reserved time interval for at least one paged station bysetting a network allocation vector.

Another access point configured for wireless communication is alsodescribed. The access point includes a processor and instructions storedin memory that is in electronic communication with the processor. Theaccess point prepares a plurality of paging messages. Each of theplurality of paging messages is associated with at least one pagingidentifier of a plurality of paging identifiers and comprises a tokennumber. Each of the plurality of paging identifiers is associated withat least one station of a set of stations. The access point alsotransmits at least one paging message to the at least one station. Theaccess point further receives a polling message from the at least onestation. The polling message includes the token number. The token numbercorresponds to the token number in one or more paging messages and isconfigured to indicate a correspondence between the polling message andthe one or more paging messages. The access point additionallyassociates the one or more paging messages with the polling message.

Another station configured for wireless communication is also described.The station includes a processor and instructions stored in memory thatis in electronic communication with the processor. The stationdetermines a schedule for transmitting a polling message to an accesspoint. The schedule is based on at least one paging identifier.

Another station configured for wireless communication is also described.The station includes a processor and instructions stored in memory thatis in electronic communication with the processor. The station selects afirst paging identifier from a plurality of paging identifiers based ona schedule by which an access point transmits paging messages comprisingthe first paging identifier. The station also transmits a request to theaccess point indicating selection of the first paging identifier.

Another station configured for wireless communication is also described.The station includes a processor and instructions stored in memory thatis in electronic communication with the processor. The station obtainsinformation relative to a time interval reserved for transmission by aplurality of stations selected from a second plurality of stations. Thestation also performs a determination as to whether to send a pollingmessage to an access point. The determination is based on the firstpaging identifier and the information relative to the reserved timeinterval.

An apparatus for reduced overhead paging is also described. Theapparatus includes means for assigning at least one paging identifier toat least one station. The apparatus also includes means for partitioninga paging identifier space into paging identifier sets. The apparatusfurther includes means for generating a paging message based on at leastone of the paging identifier sets and the at least one pagingidentifier. The apparatus additionally includes means for sending thepaging message.

Another apparatus for reduced overhead paging is also described. Theapparatus includes means for determining at least one paging identifierassigned to the apparatus. The apparatus also includes means fordetermining at least one paging identifier set corresponding to the atleast one paging identifier. The apparatus further includes means fordetermining whether a paging message corresponds to the apparatus basedon the at least one paging identifier set. The apparatus additionallyincludes means for determining whether the apparatus is paged if thepaging message corresponds to the apparatus.

An apparatus configured for wireless communication is also described.The apparatus includes means for preparing a polling message comprisinga token number. The token number corresponds to the token number in oneor more paging messages and is configured to indicate a correspondencebetween the polling message and the one or more paging messages. Theapparatus also includes means for transmitting the polling message to anaccess point.

Another apparatus configured for wireless communication is alsodescribed. The apparatus includes means for determining a transmissionschedule for a first plurality of stations. The first plurality ofstations is selected from a second plurality of stations. The apparatusalso includes means for determining a duration of a reserved timeinterval that is reserved for transmission.

Another apparatus configured for wireless communication is alsodescribed. The apparatus includes means for determining a reserved timeinterval. The apparatus also includes means for setting the reservedtime interval for at least one paged station by setting a networkallocation vector.

Another apparatus configured for wireless communication is alsodescribed. The apparatus includes means for preparing a plurality ofpaging messages. Each of the plurality of paging messages is associatedwith at least one paging identifier of a plurality of paging identifiersand comprises a token number. Each of the plurality of pagingidentifiers is associated with at least one station of a set ofstations. The apparatus also includes means for transmitting at leastone paging message to the at least one station. The apparatus furtherincludes means for receiving a polling message from the at least onestation. The polling message comprises the token number. The tokennumber corresponds to the token number in one or more paging messagesand is configured to indicate a correspondence between the pollingmessage and the one or more paging messages. The apparatus additionallyincludes means for associating the one or more paging messages with thepolling message.

Another apparatus configured for wireless communication is alsodescribed. The apparatus includes means for determining a schedule fortransmitting a polling message to an access point. The schedule is basedon at least one paging identifier.

Another apparatus configured for wireless communication is alsodescribed. The apparatus includes means for selecting a first pagingidentifier from a plurality of paging identifiers based on a schedule bywhich an access point transmits paging messages comprising the firstpaging identifier. The apparatus also includes means for transmitting arequest to the access point indicating selection of the first pagingidentifier.

Another apparatus configured for wireless communication is alsodescribed. The apparatus includes means for obtaining informationrelative to a time interval reserved for transmission by a plurality ofapparatuses selected from a second plurality of apparatuses. Theapparatus also includes means for performing a determination as towhether to send a polling message to an access point. The determinationis based on the first paging identifier and the information relative tothe reserved time interval.

A computer-program product for reduced overhead paging is described. Thecomputer-program product includes a non-transitory computer-readablemedium with instructions. The instructions include code for causing anaccess point to assign at least one paging identifier to at least onestation. The instructions also include code for causing the access pointto partition a paging identifier space into paging identifier sets. Theinstructions further include code for causing the access point togenerate a paging message based on at least one of the paging identifiersets and the at least one paging identifier. The instructionsadditionally include code for causing the access point to send thepaging message.

Another computer-program product for reduced overhead paging is alsodescribed. The computer-program product includes a non-transitorycomputer-readable medium with instructions. The instructions includecode for causing a station to determine at least one paging identifierassigned to a station. The instructions also include code for causingthe station to determine at least one paging identifier setcorresponding to the at least one paging identifier. The instructionsfurther include code for causing the station to determine whether apaging message corresponds to the station based on the at least onepaging identifier set. The instructions additionally include code forcausing the station to determine whether the station is paged if thepaging message corresponds to the station.

A computer-program product for wireless communication is described. Thecomputer-program product includes a non-transitory computer-readablemedium with instructions. The instructions include code for causing astation to prepare a polling message comprising a token number. Thetoken number corresponds to the token number in one or more pagingmessages and is configured to indicate a correspondence between thepolling message and the one or more paging messages. The instructionsalso include code for causing the station to transmit the pollingmessage to an access point.

Another computer-program product for wireless communication is alsodescribed. The computer-program product includes a non-transitorycomputer-readable medium with instructions. The instructions includecode for causing an access point to determine a transmission schedulefor a first plurality of stations. The first plurality of stations isselected from a second plurality of stations. The instructions alsoinclude code for causing the access point to determine a duration of areserved time interval that is reserved for transmission.

Another computer-program product for wireless communication is alsodescribed. The computer-program product includes a non-transitorycomputer-readable medium with instructions. The instructions includecode for causing an access point to determine a reserved time interval.The instructions also include code for causing the access point to setthe reserved time interval for at least one paged station by setting anetwork allocation vector.

Another computer-program product for wireless communication is alsodescribed. The computer-program product includes a non-transitorycomputer-readable medium with instructions. The instructions includecode for causing an access point to prepare a plurality of pagingmessages. Each of the plurality of paging messages is associated with atleast one paging identifier of a plurality of paging identifiers andcomprises a token number. Each of the plurality of paging identifiers isassociated with at least one station of a set of stations. Theinstructions also include code for causing the access point to transmitat least one paging message to the at least one station. Theinstructions further include code for causing the access point toreceive a polling message from the at least one station. The pollingmessage includes the token number. The token number corresponds to thetoken number in one or more paging messages and is configured toindicate a correspondence between the polling message and the one ormore paging messages. The instructions additionally include code forcausing the access point to associate the one or more paging messageswith the polling message.

Another computer-program product for wireless communication is alsodescribed. The computer-program product includes a non-transitorycomputer-readable medium with instructions. The instructions includecode for causing a station to determine a schedule for transmitting apolling message to an access point. The schedule is based on at leastone paging identifier.

Another computer-program product for wireless communication is alsodescribed. The computer-program product includes a non-transitorycomputer-readable medium with instructions. The instructions includecode for causing a station to select a first paging identifier from aplurality of paging identifiers based on a schedule by which an accesspoint transmits paging messages comprising the first paging identifier.The instructions also include code for causing the station to transmit arequest to the access point indicating selection of the first pagingidentifier.

Another computer-program product for wireless communication is alsodescribed. The computer-program product includes a non-transitorycomputer-readable medium with instructions. The instructions includecode for causing a station to obtain information relative to a timeinterval reserved for transmission by a plurality of stations selectedfrom a second plurality of stations. The instructions also include codefor causing the station to perform a determination as to whether to senda polling message to an access point. The determination is based on thefirst paging identifier and the information relative to the reservedtime interval.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows one example of an access point and one or more stations inwhich systems and methods for reduced overhead paging may beimplemented;

FIG. 2 is a flow diagram illustrating one configuration of a method forreduced overhead paging;

FIG. 3 is a flow diagram illustrating another configuration of a methodfor reduced overhead paging;

FIG. 4 is a diagram illustrating examples of paging messages over time;

FIG. 5 is a diagram illustrating examples of paging messages inaccordance with the systems and methods disclosed herein;

FIG. 6 is a block diagram illustrating one example of station elementsthat may be implemented for reduced overhead paging;

FIG. 7 illustrates one example of a frame format for a message;

FIG. 8 illustrates another example of a frame format for a message;

FIG. 9 illustrates another example of a frame format for a message;

FIG. 10 illustrates another example of a paging message;

FIG. 11 illustrates another example of a paging message;

FIG. 12 is a diagram illustrating a more specific example of a pagingmessage;

FIG. 13 illustrates another more specific example of a paging message;

FIG. 14 is a diagram illustrating one example of a paging mechanism;

FIG. 15 is a flow diagram illustrating one configuration of a method fordetermining an operational state;

FIG. 16 is a flow diagram illustrating one configuration of a method forcompressing a paging message;

FIG. 17 is a flow diagram illustrating another configuration of a methodfor compressing a paging message;

FIG. 18 is a flow diagram illustrating another configuration of a methodfor compressing a paging message;

FIG. 19 is a flow diagram illustrating one configuration of a method forreceiving a compressed paging message;

FIG. 20 is a flow diagram illustrating one configuration of a method forpaging receivers;

FIG. 21 is a flow diagram illustrating one configuration of a method forcontention among receivers;

FIG. 22 illustrates certain components that may be included within astation; and

FIG. 23 illustrates certain components that may be included within anaccess point.

DETAILED DESCRIPTION

The systems and methods disclosed herein may be applied to a variety ofelectronic devices. Examples of electronic devices include voicerecorders, video cameras, audio players (e.g., Moving Picture ExpertsGroup-1 (MPEG-1) or MPEG-2 Audio Layer 3 (MP3) players), video players,audio recorders, desktop computers, laptop computers, personal digitalassistants (PDAs), gaming systems, etc. One kind of electronic device isa communication device, which may communicate with another device.Examples of communication devices include telephones, laptop computers,desktop computers, cellular phones, smartphones, wireless or wiredmodems, e-readers, tablet devices, gaming systems, cellular telephonebase stations or nodes, access points, wireless gateways and wirelessrouters, etc.

An electronic device or communication device may operate in accordancewith certain industry standards, such as International TelecommunicationUnion (ITU) standards and/or Institute of Electrical and ElectronicsEngineers (IEEE) standards (e.g., Wireless Fidelity or “Wi-Fi” standardssuch as 802.11a, 802.11b, 802.11g, 802.11n and/or 802.11ac). Otherexamples of standards that a communication device may comply withinclude IEEE 802.16 (e.g., Worldwide Interoperability for MicrowaveAccess or “WiMAX”), Third Generation Partnership Project (3GPP), 3GPPLong Term Evolution (LTE), Global System for Mobile Telecommunications(GSM) and others (where a communication device may be referred to as aUser Equipment (UE), Node B, evolved Node B (eNB), mobile device, mobilestation, subscriber station, remote station, access point, station,access terminal, mobile terminal, terminal, user terminal, subscriberunit, etc., for example). While some of the systems and methodsdisclosed herein may be described in terms of one or more standards,this should not limit the scope of the disclosure, as the systems andmethods may be applicable to many systems and/or standards.

It should be noted that some communication devices may communicatewirelessly and/or may communicate using a wired connection or link. Forexample, some communication devices may communicate with other devicesusing an Ethernet protocol. The systems and methods disclosed herein maybe applied to communication devices that communicate wirelessly and/orthat communicate using a wired connection or link. In someconfigurations, the systems and methods disclosed herein may be appliedto a communication device that communicates with another device using asatellite.

Devices in a wireless network may transmit/receive information betweeneach other. Further, devices that are not activelytransmitting/receiving information in the wireless network may enter adoze state to conserve power, where the devices do not activelytransmit/receive information in the doze state. These devices mayfurther utilize paging messages to determine when to wake up from a dozestate and enter an awake state in order to transmit/receive data. Thus,improved systems, methods, and devices for transmitting and processingpaging messages may be beneficial.

Popular wireless network technologies may include various types ofwireless local area networks (WLANs). A WLAN may be used to interconnectnearby devices together, employing widely used networking protocols. Thevarious aspects described herein may apply to any communicationstandard, such as a wireless protocol.

In some aspects, wireless signals in a sub-gigahertz band may betransmitted according to the 802.11ah protocol using orthogonalfrequency-division multiplexing (OFDM), direct-sequence spread spectrum(DSSS) communications, a combination of OFDM and DSSS communications orother schemes. Implementations of the 802.11ah protocol may be used forsensors, metering and smart grid networks. Advantageously, aspects ofcertain devices implementing the 802.11ah protocol may consume lesspower than devices implementing other wireless protocols, and/or may beused to transmit wireless signals across a relatively long range, forexample about one kilometer or longer.

In some implementations, a WLAN includes various devices which are thecomponents that access the wireless network. For example, there may betwo types of devices: access points (“APs”) and clients (also referredto as stations or “STAs”). In general, an AP may serve as a hub or basestation for the WLAN and an STA serves as a user of the WLAN. Forexample, an STA may be a laptop computer, a personal digital assistant(PDA), a mobile phone, etc. In an example, an STA connects to an AP viaa WiFi (e.g., IEEE 802.11 protocol such as 802.11ah) compliant wirelesslink to obtain general connectivity to the Internet or to other widearea networks. In some implementations, an STA may also be used as anAP.

An access point (“AP”) may also comprise, be implemented as or known asa NodeB, Radio Network Controller (“RNC”), eNodeB, Base StationController (“BSC”), Base Transceiver Station (“BTS”), Base Station(“BS”), Transceiver Function (“TF”), Radio Router, Radio Transceiver orsome other terminology.

A station “STA” may also comprise, be implemented as or known as anaccess terminal (“AT”), a subscriber station, a subscriber unit, amobile station, a remote station, a remote terminal, a user terminal, auser agent, a user device, user equipment or some other terminology. Insome implementations, an access terminal may comprise a cellulartelephone, a cordless telephone, a Session Initiation Protocol (“SIP”)phone, a wireless local loop (“WLL”) station, a personal digitalassistant (“PDA”), a handheld device having wireless connectioncapability or some other suitable processing device connected to awireless modem. Accordingly, one or more aspects taught herein may beincorporated into a phone (e.g., a cellular phone or smartphone), acomputer (e.g., a laptop), a portable communication device, a headset, aportable computing device (e.g., a personal data assistant), anentertainment device (e.g., a music or video device or a satelliteradio), a gaming device or system, a global positioning system device orany other suitable device that is configured to communicate via awireless medium.

As described above, one or more of the devices described herein mayimplement the 802.11ah standard, for example. Such devices, whether usedas an STA or AP or other device, may be used for smart metering or in asmart grid network. Such devices may provide sensor applications or beused in home automation. The devices may instead or in addition be usedin a healthcare context, for example for personal healthcare. They mayalso be used for surveillance, to enable extended-range Internetconnectivity (e.g. for use with hotspots) or to implementmachine-to-machine communications.

The systems and methods described herein enable low or reduced overheadpaging. In some implementations, the systems and methods describedherein may be applied to a wireless local area network (WLAN).

IEEE 802.11 specifications define a ‘paging’ message called a trafficindication map (TIM). The traffic indication message is a bitmap, whereeach bit corresponds to a station (STA). The traffic indication map issent in beacons or dedicated traffic indication map frames. Each bit inthe bitmap may correspond to a particular station of a plurality ofstations, and the value of each bit (e.g., 0 or 1) may indicate thestate the corresponding station should be in (e.g., doze state or awakestate). Accordingly, the size of the bitmap may be directly proportionalto the number of stations in a wireless communications system.Therefore, a large number of stations in the wireless communicationssystem may result in a large bitmap. Therefore, a paging message, and insome cases the beacon or TIM frame including the paging message, may berelatively large, requiring a large amount of bandwidth to transmit. Atraffic indication map may thus be relatively large, especially if thenumber of stations to be supported will increase. Further, each stationmay need to listen to the entire paging message, and in some cases thebeacon or TIM frame including the paging message, in order to determinethe state in which it should operate. Accordingly, certain aspectsdescribed herein relate to techniques for low overhead paging, wherebythe stations selectively decode or listen to only certain pagingmessages from the access point.

The length of a traffic indication map also depends on how theassociation identifiers (AIDs) are assigned. For example, initial andfinal 0 bits are not sent. For instance, if an STA AID 1 and STA AID Nhave corresponding bits set to 1, then N bits are sent. The order ofassigning association identifiers matters.

The systems and methods disclosed herein provide approaches for limitingoverhead related to paging. In some implementations, the systems andmethod disclosed herein may modify a known paging concept by compressingthe traffic indication map bitmap representation. Additionally oralternatively, the systems and methods disclosed herein may apply ahierarchical paging mechanism, where each station only listens toselected pages. The systems and methods disclosed herein may enable useof smaller frames and enhanced power savings at stations.

The systems and methods disclosed herein may provide one or more of thefollowing approaches. An access point (AP) may assign one or more pagingidentifiers to one or more stations. A paging identifier may also bereferred to as a “power save identifier” (PS ID). The access point maypartition a paging identifier space into one or more paging identifiersets. A paging identifier set may also be referred to as a “power saveidentifier set” (PS ID set). As used herein, the “paging identifierspace” may include all paging identifiers available to an access point.Each paging identifier set may be a subset of the paging identifierspace (e.g., a paging identifier set may be smaller than or includefewer paging identifiers than the paging identifier space). However, aspecial paging identifier set may include all paging identifiers. Thesystems and methods disclosed herein may provide approaches to indexeach paging identifier set and specify which station of the pagingidentifier set is paged. In some configurations, an access point maysend only relevant paging information in a frame. For example, timeswhen paging may be sent may be defined for each station.

Regarding paging identifier assignment, each station may be assigned oneor more paging identifiers. Additionally or alternatively, one pagingidentifier may be assigned to one or more stations. It should be notedthat a paging identifier may be the association identifier (AID) in someconfigurations. For example, an association identifier may be a number(e.g., 16-bit number) that exclusively identifies one station. In otherconfigurations, the association identifier(s) and paging identifier(s)may be distinct pieces of information that are managed separately (by anaccess point, for example) in some configurations.

Regarding partitioning, paging identifier sets may be disjoint oroverlapping. For example, a single paging identifier may belong to oneor more paging identifier sets. Additionally or alternatively, pagingidentifier sets may be of different sizes or of the same size. In someconfigurations, a paging identifier set may include a continuousinterval of paging identifiers. This may provide a structure that issimilar to that of a traffic indication map. As described above, specialpaging identifier sets may include all paging identifiers. For example,a special paging identifier set may indicate broadcast, similar to adelivery traffic indication map (DTIM).

One or more approaches may be implemented to indicate which pagingidentifier set is being paged in accordance with the systems and methodsdisclosed herein. In one configuration, each paging identifier set maybe identified by an explicit identifier sent in a paging frame. Forexample, a 2 Byte field may provide indexing for 2¹⁶ paging identifiersets. Additionally or alternatively, a specific indication may be sentin the physical layer (PHY) preamble.

In another configuration, each paging identifier set may be implicitlyidentified by a sequence number associated with a sent paging frame. Forexample, a SET ID=mod (Sequence Number, 256), where “SET ID” is a pagingidentifier set number, “mod( )” is the modulo operator and “SequenceNumber” is the paging frame sequence number.

In another configuration, each paging identifier set may be implicitlyidentified by the time at which the frame is sent, for example, a set ofstations for which their associated paging identifier satisfies a givencondition with respect to the time at which the frame is sent.Alternatively, one or more stations may agree with an access point on apaging schedule.

One or more approaches may be implemented for addressing individualstations within a paging identifier set. In one configuration,individual stations may be addressed relative to the paging identifierset. For example, a bitmap of N bits may be utilized, where each bitindexes a specific station address relative to the set. The relativeposition within the set may be assigned a priori through a specificmanagement message. This management message may define the associationbetween each paging identifier and a paging identifier set.Alternatively, the relative position within the paging identifier setmay be represented by an offset from a paging identifier set value(assuming the paging identifier set value represents a starting addressfor the paging identifier set). For example, the bit in position N inthe bitmap refers to the station with a pagingidentifier=N+256*PID_Set_Number, where “PID_Set_Number” denotes a pagingidentifier set number or value. One benefit of this approach is that itprovides simple operation at the receiver (e.g., station). For instance,a receiver (e.g., station) may only need to compare a station index (STAIndex) or paging identifier value with N+256*PID_Set_Number.

In another configuration, absolute addressing may be utilized toidentify individual stations within a paging identifier set. Forexample, local or global addresses may identify individual stations. Insome implementations, partial addresses may be used. Additionally oralternatively, full paging identifiers may be utilized.

In yet another configuration, no explicit indication may be used toaddress individual stations within a paging identifier set. For example,whenever a paging identifier set is indexed, all stations correspondingto the paging identifier set are implicitly paged. Alternatively, forexample, one bit may be utilized to indicate whether all of or none ofthe stations corresponding to the paging identifier set are paged.Alternatively, all stations within a given range (e.g.,256*[PID_Set_Number: PID_Set_Number+1], where PID_Set_Number is a pagingidentifier set number or value) are paged.

At each paging epoch, a frame may be sent by an access point. Each framemay page one or more sets of stations. Each frame may include a list ofspecific stations being paged within the set. In some configurations,the schedule at which each set is paged may be defined a priori (e.g.,the access point and stations may have a defined schedule). A stationmay wake up at a time specified by the schedule.

Various configurations are now described with reference to the Figures,where like element names may indicate functionally similar elements. Thesystems and methods as generally described and illustrated in theFigures herein could be arranged and designed in a wide variety ofdifferent configurations. Thus, the following more detailed descriptionof several configurations, as represented in the Figures, is notintended to limit scope, as claimed, but is merely representative of thesystems and methods.

FIG. 1 shows one example of an access point 104 and one or more stations106 in which systems and methods for reduced overhead paging may beimplemented. The access point 104 and the one or more stations 106 maybe included in a communication system 100. In some configurations, thecommunication system 100 may operate pursuant to a wireless standard(e.g., IEEE 802.11ah). The access point 104 may communicate with the oneor more stations 106 and vice versa. For example, the access point 104and the one or more stations 106 may transmit and receive wirelesscommunication signals.

A variety of procedures may be used for transmissions in thecommunication system 100 between the access point 104 and the stations106. For example, signals may be sent and received between the accesspoint 104 and the stations 106 in accordance with orthogonalfrequency-division multiplexing/orthogonal frequency-division multipleaccess (OFDM/OFDMA) techniques. In this case, the communication system100 may be referred to as an OFDM/OFDMA system. Alternatively, signalsmay be sent and received between the access point 104 and the stations106 in accordance with code division multiple access (CDMA) techniques.In this, the communication system 100 may be referred to as a CDMAsystem.

A communication link that facilitates transmission from the access point104 to one or more of the stations 106 may be referred to as a downlink(DL) 108, and a communication link that facilitates transmission fromone or more of the stations 106 to the access point 104 may be referredto as an uplink (UL) 110. Alternatively, a downlink 108 may be referredto as a forward link or a forward channel and an uplink 110 may bereferred to as a reverse link or a reverse channel.

The access point 104 may act as a base station and provide wirelesscommunication coverage in a basic service area (BSA) 102. The accesspoint 104 and the stations 106 associated with the access point 104(that use the access point 104 for communication) may be referred to asa basic service set (BSS). It should be noted that the communicationsystem 100 may not have a central access point 104, but rather mayfunction as a peer-to-peer network between the stations 106.Accordingly, the functions of the access point 104 described herein mayalternatively be performed by one or more of the stations 106. In otherwords, an access point may be a station in some configurations.

The access point 104 may transmit a beacon signal (or simply a“beacon”), via a communication link such as the downlink 108, to thestations 106 of the system 100, which may help the stations 106 tosynchronize their timing with the access point 104, or which may provideother information or functionality. Such beacons may be transmittedperiodically. In one aspect, the period between successive transmissionsmay be referred to as a superframe. Transmission of a beacon may bedivided into a number of groups or intervals. In one aspect, the beaconmay include, but is not limited to, such information as timestampinformation to set a common clock, a peer-to-peer network identifier, adevice identifier, capability information, a superframe duration,transmission direction information, reception direction information, aneighbor list, and/or an extended neighbor list, some of which aredescribed in additional detail below. Thus, a beacon may includeinformation that is common (e.g. shared) among several devices and/orinformation specific to a given device.

In some aspects, a station 106 may be required to associate with theaccess point 104 in order to send communications to and/or receivecommunications from the access point 104. In one aspect, information forassociating is included in a beacon broadcast by the access point 104.To receive such a beacon, the station 106 may, for example, perform abroad coverage search over a coverage region. A search may also beperformed by the station 106 by sweeping a coverage region in alighthouse fashion, for example. After receiving the information forassociating, the station 106 may transmit a reference signal, such as anassociation probe or request, to the access point 104. In some aspects,the access point 104 may use backhaul services, for example, tocommunicate with a larger network, such as the Internet or a publicswitched telephone network (PSTN).

The access point 104 may include an access point paging block/module112, an access point transmit chain 118 and an access point receivechain 120. As used herein, the term “block/module” may be used toindicate that an element may be implemented in hardware (e.g.,circuitry), software or a combination of both. For example, the accesspoint paging block/module 112 may be implemented in hardware, softwareor a combination of both.

The access point transmit chain 118 may include one or moreblocks/modules for formatting and transmitting information to thestation(s) 106. For example, the access point transmit chain 118 mayinclude and/or be coupled to one or more encoders, modulators (e.g.,constellation mapper), amplifiers and/or antennas. Additionally oralternatively, the access point transmit chain 118 may perform one ormore functions such as scrambling, interleaving, precoding, etc. Theaccess point transmit chain 118 may transmit information and/or datasuch as overhead data (e.g., paging messages, beacons, controlinformation, etc.) and payload data (e.g., text, audio, voice, image,video, etc.).

In some configurations, the access point transmit chain 118 may beconfigured to wirelessly transmit messages, which may be referred to as“paging messages” that are configured to indicate to wireless deviceswhether or not the wireless devices need to wake up from a doze stateand enter an awake state as described herein. For example, the accesspoint transmit chain 118 may be configured to transmit paging messagesgenerated by the access point 104.

The access point receive chain 120 may include one or moreblocks/modules for receiving and deformatting information received fromthe station(s) 106. For example, the access point receive chain 120 mayinclude and/or be coupled to one or more decoders, demodulators,amplifiers and/or antennas. Additionally or alternatively, the accesspoint receive chain 120 may perform one or more functions such asdescrambling, deinterleaving, etc. The access point receive chain 120may receive information and/or data such as overhead data (e.g., pollingmessages, control information, etc.) and payload data (e.g., text,audio, voice, image, video, etc.).

The access point paging block/module 112 may page the one or morestations 106. For example, if a station 106 is in a power save mode(e.g., sleep state) and the access point 104 has data for transmissionto that station 106, the paging block/module 112 may generate a pagingmessage directing the station 106 to enter an awake state. As describedabove, known approaches for paging may require relatively large amountsof overhead.

In accordance with the systems and methods herein, one or more pagingidentifiers 116 may identify or correspond to one or more stations 106.Paging identifiers 116 may be utilized in paging procedures as describedherein. A paging identifier 116 may identify one or more stations 106.Additionally or alternatively, multiple paging identifiers 116 mayidentify or correspond to the same station 106. Examples of a pagingidentifier 116 include a number, a string of bits, a code, analphanumeric string, etc.

The access point paging block/module 112 may assign at least one pagingidentifier 116 to at least one station 106. For example, the accesspoint paging block/module 112 may associate at least one pagingidentifier A 116 a with a particular station 106.

The access point paging block/module 112 may partition a pagingidentifier space into paging identifier sets 114 (e.g., pagingidentifier sets A 114 a). A “paging identifier space” may be a set ofall allowed paging identifiers 116. For example, a certain number ofbits may be allocated for paging identifiers 116. Accordingly, thepaging identifier space may include all possible bit combinations orvalues for that number of bits. Partitioning the paging identifier spacemay include grouping paging identifiers 116 (e.g., deriving subsets ofthe paging identifier space). Accordingly, the access point pagingblock/module 112 may obtain paging identifier sets A 114 a, where eachpaging identifier set A 114 a includes one or more paging identifiers A116 a.

The station 106 may include a station paging block/module 126, a stationtransmit chain 124 and a station receive chain 122. The station pagingblock/module 126 may be implemented in hardware, software or acombination of both.

The station transmit chain 124 may include one or more blocks/modulesfor formatting and transmitting information to the access point 104. Forexample, the station transmit chain 124 may include and/or be coupled toone or more encoders, modulators (e.g., constellation mapper),amplifiers and/or antennas. Additionally or alternatively, the stationtransmit chain 124 may perform one or more functions such as scrambling,interleaving, precoding, etc. The station transmit chain 124 maytransmit information and/or data such as overhead data (e.g., pollingmessages, control information, etc.) and payload data (e.g., text,audio, voice, image, video, etc.).

The station receive chain 122 may include one or more blocks/modules forreceiving and deformatting information received from the access point104. For example, the station receive chain 122 may include and/or becoupled to one or more decoders, demodulators, amplifiers and/orantennas. Additionally or alternatively, the station receive chain 122may perform one or more functions such as descrambling, deinterleaving,etc. The station receive chain 122 may receive information and/or datasuch as overhead data (e.g., paging messages, polling messages, controlinformation, etc.) and payload data (e.g., text, audio, voice, image,video, etc.). In some configurations, station receive chain 122 may beconfigured to wirelessly receive paging messages.

The station paging block/module 126 may control a station's 106 response(if any) to a paging message from the access point. For example, thestation paging block/module 126 may listen for a paging message and/orinterpret the paging message. In some configurations, the station pagingblock/module 126 may only listen for paging messages at particulartimes. If a station 106 is in a power save mode (e.g., sleep state) andreceives a paging message directing the station 106 to enter an awakestate, the station paging block/module 126 may set the station 106 intoan awake state in order to receive a data transmission from the accesspoint 104.

The station paging block/module 126 may determine at least one pagingidentifier B 116 b assigned to the station 106. For example, the station106 may receive a message from the access point 104 that indicates apaging identifier assignment. The station paging block/module 126 maydesignate the paging identifier(s) B 116 b as assigned pagingidentifier(s).

The station paging block/module 126 may determine at least one pagingidentifier set B 114 b corresponding to the at least one pagingidentifier B 116 b. For example, the station 106 may receive a messagethat indicates a correspondence or an association between the at leastone paging identifier B 116 b and a paging identifier set B 114 b. Forinstance, the message may indicate which paging identifier B 116 b isincluded within which paging identifier set B 114 b.

Further detail regarding the functionality of the access point 104 andthe station(s) 106 is given above and/or below. In other words, theaccess point 104 and/or the station(s) 106 may function in accordancewith the description (e.g., one or more of the procedures, methods,approaches, structures, etc.) given above and/or below.

More detail regarding an example of an implementation of the systems andmethods is given as follows. The access point 104 and/or a station 106may be used to transmit and/or receive communications including pagingmessages. That is, either an access point 104 or a station 106 may serveas a transmitter or a receiver device of paging messages. Certainimplementations contemplate a signal detector being used by softwarerunning on memory and a processor to detect the presence of atransmitter or receiver.

The station 106 may have a plurality of operational modes. For example,the station 106 may have a first operational mode referred to as anawake state or active mode. In the awake state, the station 106 mayactively transmit and/or receive data with the access point 104.Further, the station 106 may have a second operational mode referred toas a power save mode. In the power save mode, the station 106 may be inthe “awake” state or in a “doze” or “sleep” state (where the station 106does not actively transmit/receive data with the access point 104, forinstance). For example, the station receive chain 122 (and possibly aDSP and signal detector of the station 106, for instance) may operateusing reduced power consumption in the doze state. Further, in the powersave mode, the station 106 may occasionally enter the awake state tolisten to messages from the access point 104 (e.g., paging messages)that indicate to the station 106 whether or not the station 106 needs to“wake up” (e.g., enter the awake state) at a certain time so as to beable to transmit/receive data with the access point 104.

Accordingly, in certain wireless communication systems 100, the accesspoint 104 may transmit paging messages to a plurality of stations 106 ina power save mode in the same network as the access point 104,indicating whether or not the stations 106 need to be in an awake stateor a doze state. For example, if a station 106 determines it is notbeing paged, it may remain in a doze state. Alternatively, if thestation 106 determines it may be paged, the station 106 may enter anawake state for a certain period of time to receive the page and furtherdetermine when to be in an awake state based on the page. Further, thestation 106 may stay in the awake state for a certain period of timeafter receiving the page. In another example, the station 106 may beconfigured to function in other ways when being paged or not being pagedthat are consistent with this disclosure. For example, the page mayindicate that the station 106 should enter an awake state for a certainperiod of time because the access point 104 has data to transmit to thestation 106. In some configurations, the station 106 may poll the accesspoint 104 for data by sending the access point 104 a polling messagewhen in the awake state for the period of time. In response to thepolling message, the access point 104 may transmit the data to thestation 106. As another example, a station 106 may enter a doze stateafter an access point concludes transmission of a paging message or oncethe station 106 determines that the station has not been paged by thepaging message. The station 106 may then awake when the station 106 maystart contending for the medium or transmit any message as described inthis disclosure.

As described above, each station 106 of the plurality of stations 106 inthe wireless communication system 100 may be assigned at least onepaging identifier 116 (by an access point 104, for example). Eachstation 106 may be assigned one or more such paging identifiers 116.Further, a single paging identifier 116 may be assigned to one or morestations 106. Accordingly, one or more stations 106 may be addressed bya given paging identifier 116. Further, a given station 106 may beaddressed by one or more paging identifiers 116. In some aspects, thepaging identifiers may be assigned to stations 106 during initializationof each station 106 (e.g., at the time of manufacture of the station106, at the first run time of the station 106, when a station 106 joinsa new wireless network such as wireless communication system 100, etc.).In some aspects, the paging identifiers 116 may be assigned and/oradditionally revised (e.g., reassigned), such as through communicationwith other devices in the wireless communication system 100, such as theaccess point 104. In some aspects, the access point 104 may determine orassign paging identifiers 116 for the stations 106 associated with theaccess point 104 and transmit messages indicative of the pagingidentifiers to the stations 106.

All of the paging identifiers 116 available (or alternatively assignedto the stations 106) in the wireless communication system 100 may bereferred to as a paging identifier space for the wireless communicationsystem 100 (or alternatively for the access point 104). This pagingidentifier space may be divided into a plurality of paging identifiersets 114, each set including one or more of the paging identifiers 116in a paging identifier set 114. As described above, these pagingidentifier sets 114 may be disjoint or overlapping, meaning that incertain aspects a plurality of the paging identifier sets 114 mayinclude the same paging identifier 116, and in certain aspects onepaging identifier set 114 may include a paging identifier 116 thatanother paging identifier set 114 does not include. Further, the pagingidentifier sets 114 may be of the same or different sizes, meaning theycontain the same or different numbers of paging identifiers. Further,some paging identifier sets 114 may include a continuous interval ofpaging identifiers (such as a sequential series of paging identifiers116), while some paging identifier sets 114 may include pagingidentifiers 116 that do not form a continuous interval. In one aspect, aspecial paging identifier set may include the entire set of pagingidentifiers 116. Such a special paging identifier set may be referred toas a broadcast paging identifier subset. In certain aspects, similar tohow the station 106 may be assigned a paging identifier so that thestation 106 is aware of its paging identifier as described above, thestation 106 may be assigned or given information to identify the pagingidentifier sets 114 that the station 106 is associated with. In someconfigurations, the access point 104 may utilize the paging identifier116 and paging identifier sets 114 along with paging messages asdescribed herein to enable the stations 106 to selectively receive onlycertain paging messages from the access point 104.

In some configurations, a station 106 may have an association identifier(AID). In some configurations, the one or more paging identifiers areone or more AIDs. In other configurations, AID may be distinct from theone or more paging identifiers 116 of the station 106. The AID mayidentify the station 106 within an area such as a BSA 102 (and/or withinthe BSS, for example). The AID may be used as an address or a part of anaddress and may be shorter than other addresses of the station such asan Internet protocol (IP) address or a Media Access Control (MAC)address. The AID may be included in a frame to uniquely identify asender or receiver of a message. For example, the AID may be included ina MAC header to identify a transmitting station when the AID may be usedfor addressing a frame. Further, a presentation protocol data unit(PPDU) header may include an AID or a partial AID that may be used as anearly indication of an intended receiver of the frame. Advantageously,such a PPDU header may permit early termination of processing a receivedPPDU that is indicated to be for different receiver. In some aspects,the AID may be assigned (by the access point 104, for example) atinitialization of each station 106 (e.g., at manufacture and/or when astation 106 joins a wireless network).

A station 106 may have both an AID and one or more paging identifiers116 as described herein. For instance, one paging identifier 116 mayrelate to a power save wake-up schedule or a schedule at which anassociated paging message is transmitted by an access point. Further, ifthe power save wake-up schedule of the station changes, a differentpaging identifier 116 and/or AID may be assigned to the station 106.

In some configurations, paging messages may include a token number. Thetoken number may serve as an identifier of a paging message. A station106 paged by a paging message with a token number may respond with apower save poll request message (PS-POLL) that also includes the tokennumber (taken from a beacon, for example). The token number may includeone or more of BSS identifier (BSSID), TSF, etc. The token numberaccordingly may enable an access point 104 to identify the PS-POLL ascorresponding to the paging message. Advantageously, the token numbermay be used as an identifier for the paging message sender and permitthe PS-POLL sender to transmit less data in the PS-POLL since theaddress of the sender or receiver may not be transmitted, for example.

The token number included in paging messages may vary from one pagingmessage to subsequent paging messages. The token number may change, forinstance, based on a number of stations in the BSS (and/or the BSA 102,for example), a formula, or a random generation procedure.Advantageously, changing the token number more frequently may preventissues with overlapping BSSs where each BSS utilizes token numbers orsimilar approaches.

FIG. 2 is a flow diagram illustrating one configuration of a method 200for reduced overhead paging. An access point 104 may assign 202 at leastone paging identifier 116 to at least one station 106. For example, theaccess point 104 may associate at least one paging identifier 116 with aparticular station 106. In some configurations, the access point 104 maysend a message to the station 106 indicating the assigned pagingidentifier 116.

The access point 104 may partition 204 a paging identifier space intopaging identifier sets 114. Partitioning the paging identifier space mayinclude grouping paging identifiers 116 (e.g., deriving subsets of thepaging identifier space). Accordingly, the access point pagingblock/module 112 may obtain paging identifier sets A 114 a, where eachpaging identifier set A 114 a includes one or more paging identifiers A116 a.

It should be noted that the paging identifier sets 114 may be disjointor overlapping. For example, a single paging identifier 116 may belongto one or more paging identifier sets 114. Additionally oralternatively, paging identifier sets 114 may be of different sizes orof the same size. In some configurations, a paging identifier set 114may include a continuous interval of paging identifiers 116. This mayprovide a structure that is similar to that of a traffic indication map.As described above, special paging identifier sets may include allpaging identifiers.

In some configurations, the access point 104 may send a message to thestation indicating the paging identifier sets 114 (e.g., the pagingidentifier set(s) 114 that include one or more paging identifiers 116corresponding to the station 106). For example, the message may indicatea relationship or association between one or more paging identifier sets114 and the one or more paging identifiers 116 corresponding to thestation 106. Each paging identifier set 114 may be represented by and/orindicated by a paging identifier set value. Examples of a pagingidentifier set value include a number, a string of bits, a code and/oran alphanumeric string, etc.

The access point 104 may generate 206 a paging message based on thepaging identifier sets 114 and the at least one paging identifier 116.For example, each paging message may correspond to (e.g., indicate) oneor more paging identifier sets 114. In one configuration, a pagingidentifier set 114 may be explicitly identified in the paging message.For example, the paging message may include a field (e.g., a two-bytefield) that explicitly indicates a paging identifier set 114.Additionally or alternatively, an explicit identifier may be sent in aphysical layer preamble. In another configuration, the paging messagemay implicitly indicate a paging identifier set 114 based on a sequencenumber of a paging frame. In yet another configuration, the pagingmessage may implicitly indicate a paging identifier set 114 based on thetime at which the paging message is sent.

In generating 206 the paging message, the access point 104 may determinewhether it has any data pending for transmission to a station 106 andwhether the station 106 is in a sleep state. If there is data pendingfor transmission to the station 106 and the station 106 is in a sleepstate, the access point may generate 206 a paging message directing thestation 106 to enter an awake state. For example, the access point 104may indicate that a station 106 is being paged if the individual station106 is addressed or indicated in the paging message with a correspondingpaging identifier set 114.

In one configuration, individual stations 106 may be addressed relativeto the paging identifier set 114 indicated by the paging message. Forexample, a bitmap of N bits may be utilized, where each bit indexes aspecific station address relative to the set. The relative positionwithin the set may be assigned a priori through a specific managementmessage (in assigning 202 the at least one paging identifier 116, forexample). This management message may define the association betweeneach paging identifier 116 and a paging identifier set 114.Alternatively, the relative position within the paging identifier set114 may be represented by an offset from a paging identifier set value(assuming the paging identifier set value represents a starting addressfor the paging identifier set 114, for instance).

In another configuration, absolute addressing may be utilized toidentify individual stations 106 within a paging identifier set 114. Forexample, local or global addresses may identify individual stations 106.In some implementations, partial addresses may be used. Additionally oralternatively, full paging identifiers may be utilized.

In yet another configuration, no explicit indication may be used toaddress individual stations 106 within a paging identifier set 114. Forexample, whenever a paging identifier set 114 is indexed, all stationscorresponding to the paging identifier set 114 are implicitly paged.Alternatively, for example, one bit may be utilized to indicate whetherall of or none of the stations 106 corresponding to the pagingidentifier set 114 are paged. Alternatively, all stations 106 within agiven range are paged.

The access point 104 may send 208 the paging message. For example, ateach paging epoch, a frame may be sent by the access point 104. Eachframe may page one or more sets of stations. Each frame may include alist of specific stations being paged within the set. In someconfigurations, the schedule at which each set is paged may be defined apriori (e.g., the access point 104 and stations 106 may have a definedschedule). A station 106 may wake up at a time specified by theschedule.

FIG. 3 is a flow diagram illustrating another configuration of a method300 for reduced overhead paging. A station 106 may determine 302 atleast one paging identifier 116 assigned to the station 106. Forexample, the station 106 may receive a message from an access point 104that indicates one or more paging identifiers 116 that are assigned tothe station 106.

The station 106 may determine 304 at least one paging identifier set 114corresponding to the at least one paging identifier 116. For example,the station 106 may receive a message from the access point 104 thatindicates a relationship or association between the at least one pagingidentifier 116 (assigned to the station 106) and the at least one pagingidentifier set 114.

The station 106 may determine 306 whether a paging message correspondsto the station 106 based on the at least one paging identifier set 114.For example, this determination 306 may be based on whether the pagingmessage is associated with a paging identifier set 114 that correspondsto the station 106. A paging identifier set 114 may correspond to thestation 106 if it includes a paging identifier 116 that corresponds toor identifies the station.

In making this determination 306, the station 106 may or may not receivea paging message from the access point 104. In some configurations, forexample, the station 106 may only receive paging messages according to apredetermined schedule that is based on or associated with a pagingidentifier set 114 corresponding to the station 106. For instance, thestation 106 may disregard, ignore and/or not receive paging messagesthat are sent at unscheduled times. In other configurations, the station106 may receive all of the paging messages and disregard or ignore thosepaging messages that do not correspond to a paging identifier set 114corresponding to the station 106. Accordingly, if the station 106determines 306 that a paging message does not correspond to the station106 based on the at least one paging identifier set 114 (because thepaging message is not at a scheduled time for a paging identifier set114 corresponding to the station 106 and/or because the paging messagedoes not indicate a paging identifier set 114 corresponding to thestation 106, for example), then the station 106 may determine 306 if anext paging message corresponds to the station 106 based on the at leastone paging identifier set 114.

If the paging message corresponds to the station 106 based on the atleast one paging identifier set 114 (e.g., the paging message is at ascheduled time for a paging identifier set 114 corresponding to thestation 106 and/or the paging message indicates a paging identifier set114 corresponding to the station 106), then the station 106 maydetermine 308 whether the station 106 is paged. For example, the station106 may determine whether the station 106 is addressed by the pagingmessage. As described above, the station 106 may be addressed relativeto the paging identifier set 114. For example, a particular positionrelative to the paging identifier set 114 may address the station 106.In another example, an offset from a paging identifier set value mayaddress the station 106. In yet another example, absolute addressing(with full and/or partial addresses, for example) may be utilized toaddress the station 106.

In other configurations, no explicit indication may be used forindividual stations 106 within a paging identifier set 114. For example,all stations 106 corresponding to the paging identifier set 114 may beimplicitly paged when the paging identifier set 114 is indicated.Alternatively, an indicator (e.g., one bit) may indicate whether all ornone of the stations 106 corresponding to the paging identifier set 114are paged. In another alternative, all stations 106 within a given rangeare paged.

If the station 106 is not paged, the station 106 may determine 306whether a next paging message corresponds to the station based on the atleast one paging identifier set 114. However, if the station 106 ispaged, then the station 106 may set 310 the station 106 to an awakestate. While in the awake state, for example, the station 106 mayreceive data from the access point 104.

FIG. 4 is a diagram illustrating examples of paging messages 428 overtime 430. For instance, the paging messages 428 a-c may be transmittedby the access point 104 to stations 106 in the wireless communicationsystem 100 described in connection with FIG. 1. As illustrated in FIG.4, the access point 104 is configured to transmit a plurality of pagingmessages 428 over time 430. The paging messages 428 may be sent in a TIMframe, a beacon or using some other appropriate signaling. In someimplementations, the stations 106 may be configured to listen to one ormore of the paging messages 428 as follows.

In some configurations, each paging message 428 may include one or morepaging identifier set values that correspond to the paging identifierset(s) 114 for which the paging message 428 is intended. In one example,the paging identifier set value may be a two-byte field capable ofindexing 2¹⁶ paging identifier sets 114. In another example, the pagingidentifier set value may be included in a physical layer (PHY) preambleof the paging message 428. The stations 106 may be assigned or giveninformation about the paging identifier set value(s) that refer topaging identifier sets 114 corresponding to the stations 106.Accordingly, stations 106 may receive the paging message 428. A station106 may determine whether the paging message 428 corresponds to thestation 106 based on the paging identifier set value(s) in the pagingmessage 428. For example, if the paging message 428 includes a pagingidentifier set value for a paging identifier set 114 corresponding tothe station 106, the station 106 determines the paging message 428corresponds to the station 106. Further, if the paging message 428 doesnot include a paging identifier set value for a paging identifier set114 corresponding to the station 106, the station 106 determines thatthe paging message 428 does not correspond to the station 106.

In another example, the access point 104 may be configured to transmit Npaging messages 428 in sequence (where N is any positive integer), inorder to page the stations 106 at a given time. Accordingly, each pagingmessage 428 in the sequence may be associated with a sequence number nin the N paging messages (n=1, . . . , N). Each sequence number n may beassociated with one or more paging identifier sets 114.

Accordingly, the station 106 may determine the paging message 428corresponds to the station 106 based on the sequence number n of thepaging message 428. For example, if the sequence number n of the pagingmessage 428 is associated with a paging identifier set 114 that includesa paging identifier 116 of the station 106, the station 106 determinesthe paging message 428 corresponds to the station 106. Further, if thesequence number n of the paging message 428 is not associated with apaging identifier set 114 that includes a paging identifier 116 of thestation 106, the station 106 determines that the paging message 428 doesnot correspond to the station 106.

In some configurations, the station 106 may be assigned or giveninformation regarding the relationship or association between sequencenumbers and paging identifier sets 114. This may enable a station 106 tolisten for paging messages 428 with paging identifier set(s) 114 thatcorrespond to the station 106. For example, the sequence number(s) n ofthe paging message(s) for the paging identifier set(s) 114 correspondingto the station 106 may be transmitted by the access point 104. Thestation 106 may listen for the sequence number(s). In some cases and/orconfigurations, the access point 104 may associate paging identifiersets 114 with sequence numbers. As described above, a paging identifierset value may correspond to a paging identifier set 114. Further, thestation 106 may determine whether a paging identifier set 114 isassociated with a sequence number n based on the paging identifier setvalue. For example, if the paging identifier set value of the pagingidentifier set 114 equals mod (n, 256), the paging identifier set 114 isassociated with the sequence number n. If the value of the pagingidentifier set value of the paging identifier set 114 does not equal mod(n, 256), the paging identifier set 114 is not associated with thesequence number n.

In some configurations, the access point 104 may be configured totransmit paging messages 428 at certain times (e.g., at specific timeintervals, which may repeat periodically). Accordingly, each pagingmessage 428 may be associated with a particular time interval. Each timeinterval may be associated with one or more paging identifier sets 114.In these configurations, the station 106 may determine whether thepaging message 428 corresponds to the station 106 based on the timeinterval during which the paging message 428 is transmitted. Forexample, if the time interval of the paging message 428 is associatedwith a paging identifier set 114 that includes a paging identifier 116of the station 106, the station 106 determines the paging message 428corresponds to the station 106. Further, if the time interval of thepaging message 428 is not associated with a paging identifier set 114that includes a paging identifier 116 of the station 106, the station106 determines the paging message 428 does not correspond to the station106.

In some configurations, the station 106 may be assigned or giveninformation regarding the relationship or association between timeintervals and paging identifier sets 114. This may enable the station(s)106 to listen for paging messages 428 with paging identifier set(s) 114that correspond to the station 106. In some cases and/or configurations,the access point 104 may associate paging identifier sets 114 with timeintervals. Further, the station 106 may determine whether a given pagingmessage 428 corresponds to the station 106 based on the time interval.If the station 106 determines that the paging message 428 corresponds tothe station 106, the station 106 may further determine whether thestation 106 is paged. The station 106 may set itself to a particularstate (e.g., an awake state) if the station 106 is paged. This may beaccomplished based on the content of the paging message 428 as describedbelow.

FIG. 5 is a diagram illustrating examples 532 a-c of paging messages 528a-c in accordance with the systems and methods disclosed herein. ExampleA 532 a illustrates paging message A 528 a. As illustrated, pagingmessage A 528 a includes a bitmap 534 of N bits (where N may be anypositive integer). Each bit (e.g., bit position) in the bitmap 534 maycorrespond to a particular paging identifier 116 (e.g., station 106) ofthe stations 106 that are associated with the paging identifier set(s)114 associated with the paging message A 528 a. Further, the value ofeach bit (e.g., 0 or 1) may indicate or direct a state (e.g., doze orawake) of the station 106 with the corresponding paging identifier 116.Accordingly, the station 106 may determine its operational state bydetermining the value of its corresponding bit in the bitmap 534.

In some configurations, the station 106 may be assigned or giveninformation from the access point 104 regarding which bit position(s) inthe bitmap 534 is associated with the paging identifier(s) 116 of thestation 106. For example, associations between bit positions and pagingidentifiers 116 may be set by the access point 104 or another device inthe wireless communication system 100 and communicated to the station106 via a message (e.g., a management message).

In other configurations, the paging identifier sets 114 may beassociated with paging identifier set values that represent a startingaddress for each of the paging identifiers 116 in the paging identifierset 114. For example, if the paging identifiers 116 in a pagingidentifier set 114 are sequential (e.g., 11, 12, 13, 14, etc.), thepaging identifier set 114 identifier may be 10. Accordingly, theremaining portion of a paging identifier 116 that is not part of thepaging identifier set value may be used as an index to the bitmap 534.Thus, a station 106 may use associated paging identifier(s) 116 andindex the bitmap 534 to determine the directed operation state of thestation 106. Continuing the above example, if the station 106 isassociated with paging identifier value of 11, it may look for the valueof the bit at position 1 in the bitmap 534 to determine the directedoperation state of the station 106. In some aspects, the bit in positionN of the bitmap 534 refers to the stations 106 with a paging identifiervalue=N+256*paging identifier set value.

Example B 532 b illustrates paging message B 528 b. As illustrated,paging message B 528 b may include an explicit identifier 536 of apaging identifier 116 corresponding to a station 106. Examples of theexplicit identifier 536 include a value, string of bits, code,alphanumeric string (e.g., an absolute address such as a local or globalinternet protocol (IP) address or a local or global media access control(MAC) address of the stations 106). In some configurations, the explicitidentifier 536 may be an AID. Based on the explicit identifier, astation 106 corresponding to the paging identifier set(s) 114 associatedwith the paging message B 528 b that has determined that the pagingmessage B 528 b corresponds to the station 106 may further determine ifthe station 106 is paged. For example, if the paging message B 528 bincludes an explicit identifier 536 of a paging identifier 116associated with the station 106, the station 106 determines that thestation 106 is paged. If the paging message B 528 b does not include anexplicit identifier 536 of a paging identifier 116 associated with thestation 106, the station 106 determines that it 106 is not paged.

Example C 532 c illustrates paging message C 528 c. As illustrated,paging message C 528 c may include no explicit indication of the pagingidentifiers 116 associated with stations 106 to be paged. Rather, thestations 106 that are associated with the paging identifier set(s) 114associated with the paging message C 528 c may determine that theystations 106 are paged (implicitly). Accordingly, the paging message C528 c implicitly indicates paging for all paging identifiers 116 in thepaging identifier set(s) 114 associated with the paging message C 528 c.In some configurations, a single bit may be included in paging message C528 c to indicate or direct the operational state (e.g., awake or doze)of all stations 106 associated with the paging identifier set(s) 114associated with the paging message C 528 c. For example, the value ofthe bit (0 or 1) indicates the state of all stations 106 with pagingidentifiers 116 included in the paging identifier set(s) 114corresponding to paging message C 528 c. In another configuration,presence of the bit in the paging message C 528 c (e.g., whether thepaging message C 528 c includes the bit or not) may indicate or directthe state of the stations 106. Accordingly, based on the above messagingschemes and techniques, reduced overhead paging may be achieved in thewireless communication network 100.

FIG. 6 is a block diagram illustrating one example of station 606elements that may be implemented for reduced overhead paging. One ormore of the elements 622, 638, 640, 642 may be included within thestation 106 described above in connection with FIG. 1. The station 606includes a receive chain 622 for receiving a plurality of pagingmessages from another wireless device such as the access point 104. Thereceive chain 622 may be configured to perform one or more of thefunctions of the station receive chain 122 described above in connectionwith FIG. 1.

The station 606 further includes a paging message correspondencedetermination block/module 638 for determining whether one or more ofthe paging messages correspond to the station 606 based on at least onepaging identifier set 114. For example, the paging messagecorrespondence determination block/module 638 may be configured toperform one or more of the functions described above with respect tostep 306 illustrated in FIG. 3. In some configurations, the pagingmessage correspondence determination block/module 638 may be implementedwith a processor and instructions stored in memory.

The station 606 further includes a paging determination block/module 640for determining whether the station 606 is paged. The pagingdetermination block/module 640 may be configured to perform one or moreof the functions described above with respect to step 308 illustrated inFIG. 3. In some configurations, the paging determination block/module640 may be implemented with a processor and instructions stored inmemory. The station 606 further includes a state controller 642 forsetting the operational state of the station 606. The state controller642 may be configured to perform one or more of the functions describedabove with respect to step 310 illustrated in FIG. 3. In someconfigurations, the state controller 642 may be implemented with aprocessor and instructions stored in memory. In some configurations, thepaging correspondence determination block/module 638, the pagingdetermination block/module 640 and/or the state controller 642 may beincluded in and/or coupled to the station paging block/module 126described in connection with FIG. 1.

As described above, paging identifiers 116 and paging identifier sets114 may be assigned and generated (by partitioning, for example) by theaccess point 104. In some configurations, the access point 104 mayperform these operations based on information from the station 106 aboutwhen the station 106 requests such pages. This may lead to significantoverhead at the access point 104 for performing such scheduling toaccommodate requests of multiple stations 106.

In some configurations, additionally or alternatively, the access point104 may transmit paging messages for particular paging identifiers 116at specific time intervals. For example, a paging message comprising abitmap of particular paging identifiers 116 may be transmitted atspecific timer intervals. Other paging messages may include bitmaps fordifferent paging identifiers 116 and may be transmitted at differentintervals. For example, a first paging message may include a bitmap fora first paging identifier set 114 (e.g., paging identifiers 1-32). Thefirst paging message may be transmitted once per three beacons (e.g.,beacon 1, 4, 7, etc.). Further, a second paging message may include abitmap for a second paging identifier set 114 (e.g., paging identifiers33-64). The second paging message may be transmitted once per threebeacons following the first paging message (e.g., beacon 2, 5, 8, etc.)Further, a third paging message may include a bitmap for a third pagingidentifier set 114 (e.g., paging identifiers 65-96). The third pagingmessage may be transmitted once per three beacons following the secondpaging message (e.g., beacon 3, 6, 9, etc.). A station 106 may beassigned a paging identifier 116 from the access point 104 (e.g., apaging identifier 116 in either the first, second, or third pagingidentifier set 114) that is transmitted according to a particularschedule (e.g., interval schedule). Accordingly, the station 106 may beassigned a particular paging message transmission schedule from a finitegroup of schedules. This information can further be used as a timingsource for the station 106 and reduces overhead at the access point 104.In some configurations, the station 106 may request a paging messageschedule assignment. For example, the access point 104 and the station106 may agree to a particular paging message schedule.

In some configurations, after receiving a paging message from the accesspoint 104 indicating the access point 104 has data for the station 106,the station 106 may send a polling message to the access point 104 inorder to receive the data from the access point 104. In some aspects,multiple stations 106 may be paged by the access point 104 as describedabove. Accordingly, the multiple stations 106 may contend for one ormore communication channels with the access point 104 in order totransmit the polling messages to the access point 104. If severalstations 106 attempt to send polling messages to access points such asthe access point 104 at the same time, the polling messages may collide.In some configurations, the schedule of when the station 106 transmits apolling message may be based on the paging identifier 116 of the station106 and/or the paging identifier set 114(s) to which the station 106belongs in order to reduce the likelihood of collisions as describedbelow.

In one configuration, a station 606 may determine when to poll theaccess point 104 for data based on the paging identifier 116 of thestation 106 upon receiving a paging message indicating that the accesspoint 104 has data for the station 106. For example, as described abovewith respect to example A 532 a in FIG. 5, the paging message mayinclude a bitmap of N bits (where N is any positive integer). Each bitin the bitmap may correspond to a particular paging identifier 116 orstation 106 of the stations 106 that are associated with the pagingidentifier set(s) 114 associated with the paging message. Further, thevalue of each bit (e.g., 0 or 1) may indicate the state thecorresponding station 106 with such a paging identifier 116 should be in(e.g., doze or awake). Stations 106 associated with a bit having a valueof 1 may determine that the station 606 is paged (e.g., the access point104 has data to transmit to the station 106) based on the bit value. Insome configurations, the station 106 may determine a time to poll theaccess point 104 based on the position of the bit corresponding to thestation 106 in the bitmap. For example, if the bit associated with thestation 106 is the x^(th) bit, the station 106 may poll the access point104 at a time based on a function of x (e.g., x*n microseconds (μs)after receiving the paging message, where n is any positive integer). Inanother example, the station 106 may determine a time to poll the accesspoint 104 based on a hash function of the paging identifier 116 (e.g., ahash of the paging identifier 116 and the timestamp of the pagingmessage).

In another configuration, the station 106 may determine a time to startcontending for a channel to transmit a polling message to the accesspoint 104 based on the paging identifier 116 (instead of determining anexact time to poll the access point 104, for example). For instance, ifthe bit associated with the station 106 is the x^(th) bit, the station106 may contend for the channel at a time based on a function of x(e.g., x*n μs after receiving the paging message, where n is anypositive integer). In another example, the station 106 may determine atime to contend for the channel based on a hash function of the pagingidentifier 116 (e.g., a hash of the paging identifier 116 and thetimestamp of the paging message).

In yet another configuration, the station 106 may use a backoff counter(similar to the backoff counter of the IEEE 802.11 standard) todetermine when to transmit a polling message to the access point 104.For example, the station 106 may countdown a backoff counter from astarting value, and when the counter reaches 0, the station 106 maytransmit the polling message. The station 106 may also determine if thechannel is active (there is traffic on the channel) or the channel isidle (there is no traffic on the channel) while counting down. If thechannel is active, the station 106 may freeze the countdown until thechannel is idle again. The station 106 may determine the starting valueof the backoff counter based on the paging identifier 116. For example,if the bit associated with the station 106 is the x^(th) bit, thestation 106 may set the backoff counter at a value based on a functionof x (e.g., x*n μs after receiving the paging message, where n is anypositive integer). In another example, the station 106 may set thebackoff counter at a value based on a hash function of the pagingidentifier 116 (e.g., a hash of the paging identifier 116 and thetimestamp of the paging message).

The use of paging identifiers 116 and paging identifier sets 114 fortransmitting and receiving paging messages as described above may beperformed through message exchange between the stations 106 and theaccess point 104. The messages may take a variety of different formats.Below are described some of the formats that different messages may takeand the usage of such messages with respect to the aspects describedherein.

FIG. 7 illustrates one example of a frame format for a message 700. Themessage 700 may be transmitted from the station 106 to the access point104 to set up paging intervals and/or obtain a paging identifier 116.The message 700 may be referred to as a page setup request message 700.As shown in FIG. 7, the message 700 includes an equipment identifier(EID) field 744 comprising 1 byte, followed by a frame length (LEN)field 746 comprising 1 byte, followed by a control field 748 comprising1 byte, followed by one or more time start fields 750 a-b and timeperiod fields 752 a-b, each comprising at least 3 bytes. The time startfields 750 a-b indicate a time the station 106 requests a paginginterval to start (a time period where the station 106 will wake up) andthe time period fields 752 a-b indicate a time period for the pagingintervals. The times may be indicative of, for example, a number ofbeacon periods, a number of seconds, a number of microseconds, amultiple of a number of microseconds, or some other unit of measure. Thecontrol field 748 may indicate the manner in which the time isindicated. The response from the access point 104 to the message 700 maybe a page setup response message or an acknowledgement (ACK) (e.g., anenhanced ACK with a time indication).

FIG. 8 illustrates another example of a frame format for a message 800.The message 800 may be transmitted from the station 106 to the accesspoint 104 to set up paging intervals and/or obtain a paging identifier116. The message 800 includes the same fields as the message 700described in connection with FIG. 7 (e.g., an EID field 844, a LEN field846, a control field 848, one or more time start fields 850 a-b and oneor more time period fields 852 a-b). However, the message 800 furtherincludes one or more paging identifier (PID) (e.g., paging identifier116) fields 854 a-b comprising 2 bytes before each time start field 850a-b and time period field 852 a-b. The PID field 854 may indicate aspecific paging identifier 116 the station 106 requests for schedulingduring the associated time start and time period.

FIG. 9 illustrates another example of a frame format for a message 900.The message 900 may be transmitted from the access point 104 to thestation 106. The message 900 may be referred to as a page setup responsemessage 900. The message 900 may be sent by the access point 104 inresponse to receipt of a message (e.g., the message 700 in FIG. 7 or themessage 800 in FIG. 8) from the station 106. The message 900 may includesimilar fields (e.g., an EID field 944, a LEN field 946, a control field948, one or more time start fields 950 a-b, one or more time periodfields 952 a-b and one or more PID fields 954 a-b) to those included inthe message 800 described in connection with FIG. 8. The control field948 may be used to indicate the status (e.g., denied, accepted) of therequest for a paging interval and/or paging identifier 116 from thestation 106. The time start field 950 may indicate an assigned starttime for paging intervals, the time period field 952 may indicate theduration of the interval, and the PID field 954 may indicate the pagingidentifier 116 assigned for the given start time and interval. Thestation 106 may respond to receipt of the message 900 with transmissionof an ACK.

FIG. 10 illustrates another example of a paging message 1000. The pagingmessage 1000 may be similar to paging message A 528 a described inconnection with FIG. 5. As illustrated, the paging message 1000 includesan EID field 1044, a LEN field 1046, a control field 1048, and one ormore offset fields 1056 a-b and optionally one or more bitmaps (BMAP)1058 a-b. The offset field 1056 may indicate the offset from the pagingidentifier 116 that the station 106 should use to index the bitmap 1058as described above with respect to example A 532 a described inconnection with FIG. 5. For example, an offset of 100 may indicate thatthe paging identifier 101 is at the 1 position (101-100) of the bitmap.In another aspect, the offset field may indicate the paging identifierset 114 that is paged.

FIG. 11 illustrates another example of a paging message 1100. The pagingmessage 1100 may be similar to paging message B 528 b described inconnection with FIG. 5. As illustrated, the paging message 1100 includesan EID field 1144, a LEN field 1146, a control field 1148, and one ormore PID fields 1154 a-n comprising a paging identifier list. Eachpaging identifier field 1154 may include or indicate a particular pagingidentifier 116, and the station 106 may determine that the station 106is paged if its paging identifier 116 is listed in one of the PID fields1154 a-n, as described above with example B 532 b in connection withFIG. 5.

FIG. 12 is a diagram illustrating a more specific example of a pagingmessage 1228. A full bitmap (in accordance with known approaches, e.g.,a full TIM) may include a sequence of 0/1 bits indicating whether thereis data for a specific station. The index of the station in that case isthe position of the bit in the bitmap (e.g., if the corresponding bit is1, then there is data for the station and if the corresponding bit is 0,then there is no data for the station). In accordance with the systemsand methods disclosed herein, a bitmap may be compressed in order toobtain a compressed paging message (as illustrated in FIG. 12, forexample). Example A 1232 a illustrates a paging message 1228 with acompressed bitmap, such as a compressed version of a trafficidentification map (TIM). The paging message 1228 may be similar topaging message B 528 b described in connection with FIG. 5. Asillustrated, the paging message 1228 includes an EID field 1244, a LENfield 1246, an optional control field 1248, and one or more sub-bitmapelements 1260 a-n. The control field 1248 may indicate the type ofcompression used. The one or more sub-bitmap elements 1260 a-n may besent in a single paging message (or frame) in order to cover multiplestations 106.

Example B 1232 b illustrates the structure of one of the sub-bitmapelements 1260. In particular, a first field indicates an offset value1262 that is used to identify the index of a paged station 106. In oneconfiguration, the first field comprises 13 bits. A sub-bitmap element1260 may identify a particular station. For example, a station (e.g.,paged station) index may be computed as a sum of the offset value andthe bit position in a variable-length bitmap 1266. A second fieldidentifies the length 1264 of the variable-length bitmap 1266. Thelength 1264 may be indicated in byte units. In one configuration, thesecond field comprises 3 bits. If the value of the length 1264 is equalto zero, then the only station 106 that is paged is the station 106 withindex equal to the offset value 1262 contained in the first field. Ifthe value of the length 1264 is greater than zero, then the value of thelength 1264 indicates the number of bytes in the variable-length bitmap1266. A third field identifies the variable-length bitmap 1266. Thevariable-length bitmap 1266 is of variable length because trailing zeroscan be omitted and assumed to be implicitly zeros (unless anothersub-bitmap element 1260 indicates otherwise). In one configuration, thelength of the variable-length bitmap may be from 0 bytes to 7 bytes. Inanother configuration, the value indicated by the length field may bemapped to different lengths of the variable length bitmap 1266. Forexample, 0 may indicate that the variable length bitmap 1266 is notpresent, 1 may indicate that the variable length bitmap 1266 is 1 byte,2 may indicate that the variable length bitmap 1266 is 4 bytes, 3 mayindicate that the variable length is 8 bytes, etc. It should be notedthat the compression described in connection with FIG. 12 may be appliedin conjunction with one or more of the methods, procedures, approachesand/or structures described herein. Additionally, all or part of thecompression as described in connection with FIG. 12 may be combined withone or more of the methods, procedures, approaches and/or structuresdescribed herein.

FIG. 13 illustrates another more specific example of a paging message1328. In particular, example A 1332 a illustrates a paging message 1328including a compressed bitmap, such as a compressed version of a trafficidentification map (TIM) as described above. By way of example, and notlimitation, compression applied in this paging message 1328 may be usedwith a low-density bitmap (e.g., a bitmap in which the number of ones ismuch less than the number of zeros). The paging message 1328 may besimilar to paging message B 528 b described in connection with FIG. 5above. As illustrated, the paging message 1328 includes an EID field1344, a LEN field 1346, a control field 1348 and a compressed TIMInformation Element (TIM IE) 1368. The control field 1348 may indicatethe type of compression used.

Example B 1332 b illustrates the structure of the compressed TIM IE1368. The structure employs running length sequences 1376 obtained byuse of a running-length encoding (RLE) method to process the originalbitmap. In particular, a first field 1370 indicates the value of thefirst bit in the sequence of a bitmap to be compressed. This value maybe either “1” or “0”. A second field 1372 indicates a number N ofrunning length sequences (e.g., N=2^(n), where n is the number of bitsincluded in the second field 1372). In one aspect, the second field 1372is formed of n=13 bits (in this way, N can cover at least up to 6000,for example). A third field 1374 indicates the number of bits L of eachrunning length sequence (e.g., L=2^(l), where l is the number of bitsforming the third field 1374). In one aspect, the third field 1374 isformed of l=4 bits. A fourth field 1376 includes the running lengthssequences 1376. The total number of bits forming fourth field 1376 isN*L. In one aspect, the number of bits L may be selected as L=ceil(log₂R), where R=max([r1, r2, . . . , rN]), with [r1, r2, . . . , rN]corresponding to the sequence of the N running length sequences. Fromthis compressed TIM IE 1368, the stations can losslessly reconstruct theoriginal bitmap. The approach described in connection with FIG. 13 mayoperate in conjunction with one or more of the methods, procedures,approaches and/or structures described herein. Additionally, all or partof the approach as described in connection with FIG. 13 may be combinedwith one or more of the methods, procedures, approaches and/orstructures described herein.

FIG. 14 is a diagram illustrating one example of a paging mechanism. Thepaging mechanism shown may be used by the access point 104 and stations106 in the wireless communication system 100 described in connectionwith FIG. 1. As illustrated, time increases from left to right over thetime axis 1484. The access point 104 may be configured to transmit aplurality of paging messages 1478 a-b. By way of example and notlimitation, a paging message 1478 a may comprise a sequence of bits asillustrated. The paging message 1478 may be generated as describedabove.

After transmission of a paging message 1478, a time interval 1482 may bereserved for the paged stations 106. The reservation may be achieved bytransmitting a message (e.g., a paging message, other message) to causenon-paged stations to defer access to the medium for the duration of thereserved period. In some implementations, the deferred access can beachieved by setting a duration field value of a reserving frame so thatnon-paged stations can set their network allocation vector (NAV). Inother words, an access point 104 may determine a reserved time intervaland may set the reserved time interval for at least one paged station106 by setting a NAV.

During the reserved time interval 1482, the paged stations 106 can sendrequests 1480 a-b to the access point 104 (e.g., Power Saving polls(PS-POLL) requests) and receive a response from the access point 104.Multiple paged stations 106 can contend during time interval 1482 inaccordance with various methods, as described herein. Stations 106 thathave not been paged may not contend during time interval 1482. Once thetime interval 1482 is over, stations 106 may start contending to sendrequests to the access point 104. The access point 104 determines theduration of the time interval 1482. The time interval 1482 may besufficient for all the paged stations 106 to send requests to the accesspoint 104 and receive a response from the access point 104. By way ofexample, and not limitation, the duration of time interval 1482 may be afunction of the number of paged stations 106.

FIG. 15 is a flow diagram illustrating one configuration of a method1500 for determining an operational state. In some configurations, astation 106 described in connection with FIG. 1 may perform the method1500. The station 106 may receive 1502 a plurality of paging messagesfrom the access point 104.

The station 106 may determine 1504 whether to listen to one or morepaging messages of the plurality of paging messages based on thetechniques described herein (e.g., based on a paging identifier set).Determining 1504 whether to listen to one or more paging messages may beone example of determining 306 whether a paging message corresponds tothe station 106 based on the at least one paging identifier set asdescribed above in connection with FIG. 3. For instance, the station 106may make the determination 1504 based on a paging identifier set 114included in the paging message, a sequence number n of the pagingmessage or a time interval in which the paging message was transmitted.

If the station 106 determines not to listen to one or more pagingmessages, operation ends for those one or more paging messages. However,if the station 106 determines to listen to one or more paging messages,operation continues for those one or more paging messages.

If the station 106 determines 1504 to listen to one or more pagingmessages, the station 106 may determine 1506 whether the one or morepaging messages identifies an operational state of the station 106 inaccordance with the techniques described herein. Determining 1506whether the one or more paging messages identify an operational state ofthe receiving device may be one example of determining 308 whether thestation 106 is paged as described in connection with FIG. 3 above. Forinstance, the station 106 may make the determination 1506 based on abitmap included in the paging message, a station identifier (e.g., apaging identifier or some indication corresponding to the station 106)included in the paging message or based on the paging message includingno explicit indicator. If the station 106 determines 1506 that the oneor more paging messages do not identify an operational state of thestation 106, operation may end (but may recur for one or more additionalpaging messages, for example).

If the station 106 determines 1506 that the one or more paging messagesidentify an operational state of the station 106, the station 106 mayset 1508 its operational state based on the one or more paging messagesas described herein. For example, if the one or more paging messagesdirect the station 106 to enter an awake state, the station 106 mayenter an awake state.

FIG. 16 is a flow diagram illustrating one configuration of a method1600 for compressing a paging message. By way of example and notlimitation, examples of possible compressed paging messages that may beobtained in accordance with this method 1600 are paging messages 1228and 1328 as described above in connection with FIGS. 12 and 13. Atransmitting device (e.g., the access point 104 or an apparatusassociated with the access point 104) may schedule 1602 a plurality ofreceivers (e.g., stations 106) to be paged. The transmitting device maygenerate 1604 a paging message. The paging message may identify one ormore of the plurality of scheduled receivers.

The transmitting device may compress 1606 the paging message. Variousapproaches may be employed for performing the compression as describedherein (through the use of paging identifiers 116 and paging identifiersets 114, for example).

The transmitting device may transmit 1608 the compressed paging messageto the one or more of the plurality of scheduled receivers. In certaincases (e.g., with high-density bitmap or a bitmap in which the number ofzeros is much less than the number of ones), the transmitting device maychoose a fraction (e.g., subgroup or subset) of the plurality ofreceivers to be paged for inclusion in the paging message. In someconfigurations, scheduling the plurality of devices may be done, forexample, in a round robin manner. The method 1600 described inconnection with FIG. 16 may operate in conjunction with one or more ofthe methods, procedures, approaches and/or structures described herein.Additionally, all or part of the method 1600 as described in connectionwith FIG. 16 may be combined with one or more of the methods,procedures, approaches and/or structures described herein.

FIG. 17 is a flow diagram illustrating another configuration of a method1700 for compressing a paging message. For example, the method 1700 maybe performed by an access point 104 in order to generate the pagingmessage 1228 described in connection with FIG. 12. The transmittingdevice (e.g., the access point 104 or an apparatus associated with theaccess point 104) may define 1702 a sub-bitmap element 1260.

The transmitting device may insert 1704 information directed atidentifying the index of a paged receiver (e.g., station 106) into thesub-bitmap element 1260. The information may be, for example, in theform of an offset field 1262 and a length field 1264 as described abovein connection with FIG. 12.

The transmitting device may insert 1706 a variable-length bitmap 1266into the sub-bitmap element 1260. The transmitting device may transmit1708 one or more sub-bitmap elements 1260 in a single paging message(within a single TIM frame, for example). This may be done in order tocover multiple stations within a single frame. The method 1700 describedin connection with FIG. 17 may operate in conjunction with one or moreof the methods, procedures, approaches and/or structures describedherein. Additionally, all or part of the method 1700 as described inconnection with FIG. 17 may be combined with one or more of the methods,procedures, approaches and/or structures described herein.

FIG. 18 is a flow diagram illustrating another configuration of a method1800 for compressing a paging message. For example, the method 1800 maybe performed by an access point 104 in order to generate the pagingmessage 1328 described in connection with FIG. 13. The transmittingdevice (e.g., the access point 104 or an apparatus associated with theaccess point 104) may receive 1802 a bitmap to be compressed. The bitmapmay be similar to the bitmap as described above.

The transmitting device may compress 1804 the bitmap by obtainingrunning-length sequences. The sequences may be obtained by using arunning-length encoding (RLE) technique.

The transmitting device may define 1806 an information element (e.g., acompressed TIM IE 1368). The transmitting device may insert 1808 therunning length sequences into the information element.

The transmitting device may insert 1810 information relative to therunning length sequences into the information element. For example, theinformation may comprise the information contained in the first bitfield 1370, sequence length N field 1372 and length of L field 1374 asdescribed above in connection with FIG. 13. The method 1800 described inconnection with FIG. 18 may be used, for example, with a low-densitybitmap (e.g., a bitmap in which the number of ones is much less than thenumber of zeros). However, it should be noted that the method 1800 maybe applied in other cases or scenarios.

FIG. 19 is a flow diagram illustrating one configuration of a method1900 for receiving a compressed paging message. For example, this method1900 may be applicable to receive one or more of the paging messages1228 and 1328 described above in connection with FIGS. 12 and 13. Areceiver (e.g., a station 106) may receive 1902 a compressed pagingmessage from a transmitting device (e.g., the access point 104 or anapparatus associated with the access point 104).

The receiver may reconstruct 1904 a paging message based on thecompressed paging message. The approach for reconstructing the pagingmessage may depend on the approach used for compressing the originalpaging message.

The receiver may select 1906 a first receiver identifier from aplurality of receiver identifiers that are included in the pagingmessage. The receiver may transmit 1908 a request to the transmittingdevice indicating the selection of the first receiver identifier. Themethod 1900 described in connection with FIG. 19 may operate inconjunction with one or more of the methods, procedures, approachesand/or structures described herein. Additionally, all or part of themethod 1900 as described in connection with FIG. 19 may be combined withone or more of the methods, procedures, approaches and/or structuresdescribed herein.

During a TIM interval, contention may be performed by a set of pagedstations 106 that are scheduled for uplink transmission to the accesspoint 104, and a set of stations 106 that are non-paged (which may stillhave packets to transmit to the access point 104). The stations 106 mayreceive a paging indication that data is pending at the access point forthat station 106. Once the station 106 knows this, the station 106 maybe configured to send a signal to request the pending data. For example,the signal may include an uplink frame called PS-POLL and/or otherframe(s) to request that pending data. As described above, if severalstations 106 attempt to send messages (e.g., polling messages) to anaccess point (e.g., access point 104) at the same time, the messages maycollide. Moreover, it may be desirable in some implementations toguarantee access to the paged stations 106. Accordingly, in someaspects, a schedule for station transmissions may be based on a pagingmechanism as described herein, in order to reduce the likelihood ofcollision and guarantee access to the paged stations 106.

FIG. 20 is a flow diagram illustrating one configuration of a method2000 for paging receivers. A transmitting device (e.g., the access point104 or an apparatus associated with the access point 104) may determine2002 a transmission schedule for a first plurality of receivers (e.g.,stations 106). The first plurality of receivers may have data pendingfor transmission at the transmitting device. The first plurality ofreceivers may be selected from a second plurality of receivers. Thesignal may also include scheduling information that may identify atransmission schedule for the first plurality of receivers (e.g., thestations 106).

The transmitting device may determine 2004 a reserved time interval. Thereserved time interval may be reserved for the scheduled first pluralityof receivers. The transmitting device may transmit 2006 a paging messageto the second plurality of receivers. For example, the paging messagemay include information relative to the duration of the reserved timeinterval. The method 2000 described in connection with FIG. 20 mayoperate in conjunction with one or more of the methods, procedures,approaches and/or structures described herein. Additionally, all or partof the method 2000 as described in connection with FIG. 20 may becombined with one or more of the methods, procedures, approaches and/orstructures described herein.

FIG. 21 is a flow diagram illustrating one configuration of a method2100 for contention among receivers. Receivers (e.g., stations 106) mayreceive 2102 a paging message from a transmitting device (e.g., theaccess point 104 or an apparatus associated with the access point 104).

Each receiver may obtain 2104 information relative to a reserved timeinterval (e.g., to the duration of the reserved time interval). Forexample, each receiver may obtain 2104 this information in a managementframe, paging frame or other signaling. As described above, in someimplementations, the reservation may be achieved by having the pagingmessage (or an additional message sent after the initial paging message,for example) to cause non-paged stations to defer access to the mediumfor the duration of the reserved period. The deferred access can beachieved, for example, by setting a duration field of the paging messageor reserving frame so that non-paged stations may set their NAV for theappropriate time.

Each receiver may determine 2106 whether it is a paged receiver based onthe content of the paging message. For example, during the reserved timeinterval, only paged receivers may contend to send requests (e.g.PS-POLL requests) to the transmitting device. Paged receivers maycontend 2108 to send a request (to the transmitting device, forexample).

Non-paged receivers may wait 2110 for expiry of the reserved timeinterval. The receiver(s) may contend 2112 to send a frame upon expiryof the reserved time interval. The method 2100 described in connectionwith FIG. 21 may operate in conjunction with one or more of the methods,procedures, approaches and/or structures described herein. Additionally,all or part of the method 2100 as described in connection with FIG. 21may be combined with one or more of the methods, procedures, approachesand/or structures described herein.

Various approaches for medium contention may be envisaged to be used bythe receivers in any of the methods and processes described above. Byway of example and not limitation, contention may be employed inconjunction with the method 2100 described in connection with FIG. 21.

A paging message (as described in connection with any of the methodsabove, for example) may implicitly or explicitly define an ordering forthe stations 106. For example, if the TIM bitmap indicates that bothstation 1 and station 2 are paged, then the TIM bitmap may alsoimplicitly or explicitly indicate whether station 1 is before or afterstation 2. For instance, the order may be determined by the order inwhich the paged stations appear in the bitmap representation. Consider abitmap {0, 1, 0, 0, 1, 1}, where the station 106 associated with the bitin position 2 is assumed to be before the station associated with thebit in position 5. Thus, a schedule indicated by the access point 104and/or determined by a station 106 may indicate an order. In someconfigurations, the ordering for the stations may be randomized (basedon a TSF or other indications, for example).

In some implementations, the compressed bitmap may be expressed as alist of station identifiers. In this case, the sequence in which thestation identifiers appear in the list may determine the order. Considerthe list {13, 25, 5, 22}, where the station associated with identifier“13” is assumed to come before station identified by “5.” In anotherconfiguration, the order may be derived from the value of the stationidentifier irrespective of the message representation.

In some implementations, the position of the station within the TIMbitmap sequence may be a function of the position of the station 106 asdescribed above. The order may further be dependent on otherindications, the indications being either included in the paging messageor assumed to be known at the stations 106. For example, the indicationmay include the Timing Synchronization Function (TSF) within the pagingmessage. In such an implementation, the first station 106 may be the onewhose identifier is set to “1” and has a position within the TIM bitmapsequence that is first in the order after the position associated withthe 12 least significant bits (LSBs) of the TSF. Many other functionsincorporating various indications may be included to achieve a similarresult as that based on the TSF. One beneficial result of including theTSF in the computation of the order is that the order may be changed ateach transmission, provided that the portion of the used TSF isdifferent at each transmission.

In some implementations, the sender of the paging message may determinethe order of the paged stations according to any criteria including theusage of the ordering information. For example, the sender may order thestations based on their Quality of Service (QoS) requirements, powersaving requirements or other performance parameters. It may bedesirable, in some implementations, for the sender of the paging messageto include in the message an explicit indication of the order. Thisexplicit indication of the order may not be based on the TIM bitmap butrather other factors as described above.

A further approach includes assigning to a station 106 a deterministicbackoff value. The station may be configured to use the backoff value toinitialize a backoff counter for the distributed coordinationfunction/enhanced distributed channel access (DCF/EDCA) accessprocedure. The initial value of the backoff counter may be based on theorder of the paged station. The order of the paged station may beobtained using one or more of the approaches and/or methods describedabove.

A further approach includes assigning to each paged station 106 a timeat which to start the contention procedure for sending the PS-POLL. Inone configuration, the contention procedure may start for all stations106 at a defined time, for instance, immediately after the end of thepaging message or after an additional message sent after the pagingmessage (e.g., the message reserving the medium described above). Insome implementations, the start of the contention may be set to adifferent time per each station 106. For instance, the time a station isallowed to start the contention to send the PS-POLL may be determinedbased on the order of the stations defined by the paging message asdescribed above. In one implementation, a time slot may be defined and astation 106 may be allowed to start the contention after a time that isa multiple of time slots times the position of the station 106. The timeslot may be, for instance, known by all the stations 106 a priori orcommunicated by the sender of the paging message. The interval betweensubsequent devices in the order may correspond to the beacon interval orthe number of TIM bitmap sequence bits that are set to “1.”Alternatively, the interval may be a fixed time during which a typicalPS-POLL or Data or ACK exchange could take place. In further aspects,after entering an awake state, stations 106 may sense or listen to themedium for an additional time prior to contending for the medium.

In some implementations, the system may be configured to assign to astation 106 a precise time slot to access the medium. In this aspect,the station may be configured to send the PS-POLL at the designatedtime. The assignment of the time slot may be based on the position ofthe station identifier within the paging message.

Another approach includes assigning to one or all the stations 106 aContention Window (CW) value. The station 106 may be configured to usethe CW value as described by the DCF/EDCA medium access procedure. Inone implementation, all the paged stations 106 may be configured to usethe same CW value when contending for sending the PS-POLL after thepaging message. The CW value may be a function of the number of stationspaged by the paging message. For instance, the CW may be larger if thenumber of paged stations is large and may be smaller if the number ofpaged stations is small. In another aspect, different stations may beassigned different CW values, for instance, depending on the orderindicated in the paging message.

In some configurations, a station 106 may initialize a backoff valuebased on the CW to determine when to contend for the medium. For a firsttransmission, the initialized backoff value may be a random number in aninterval [0, CW]. However, if the station 106 is unable to successfullytransmit the first transmission, an N^(th) transmission attempt may beinitialized with a backoff value having a random value within aninterval of [0, N*CW] or [0, N+CW]. Advantageously, the use of suchbackoff value intervals for the N^(th) transmission attempts may preventuse of a random value within an exponentially based backoff valueinterval such as [0, (2^(N))*CW].

Accordingly, the time until the station 106 successfully transmits amessage may be shortened, and the station 106 may enter a doze statesooner and consume less power.

In some configurations, if a station 106 does not receive a response toa PS-POLL, the station 106 may again transmit the PS POLL in a currentpaging interval (e.g., one interval for transmitting PS-POLLs). When thestation 106 transmits the PS-POLL again in the current paging interval,the station 106 may, for example, send the PS-POLL a point coordinationfunction (PCF) interframe space (PIFS) time after the previous PS-POLLor the station 106 may use a back-off procedure as described herein. Onthe other hand, in some configurations, if the station 106 does notreceive a response to a PS-POLL, the station 106 may defer transmissionof the PS-POLL until a next paging interval (e.g., another interval fortransmitting PS-POLLs different from the current paging interval). Itshould be noted that two or more of the access approaches describedabove (e.g., assignment of the contention window, assignment of theinitial backoff value and/or assignment of the time for the contentionstart) may be used concurrently.

FIG. 22 illustrates certain components that may be included within astation 2206. One or more of the stations 106, 606 described above maybe implemented in accordance with the station 2206 described inconnection with FIG. 22. The station 2206 includes a processor 2215. Theprocessor 2215 may be a general purpose single- or multi-chipmicroprocessor (e.g., an ARM), a special purpose microprocessor (e.g., adigital signal processor (DSP)), a microcontroller, a programmable gatearray, etc. The processor 2215 may be referred to as a centralprocessing unit (CPU). Although just a single processor 2215 is shown inthe station 2206 of FIG. 22, in an alternative configuration, acombination of processors (e.g., an ARM and DSP) could be used.

The station 2206 also includes memory 2201 in electronic communicationwith the processor 2215 (i.e., the processor 2215 can read informationfrom and/or write information to the memory 2201). The memory 2201 maybe any electronic component capable of storing electronic information.The memory 2201 may be random access memory (RAM), read-only memory(ROM), magnetic disk storage media, optical storage media, flash memorydevices in RAM, on-board memory included with the processor,programmable read-only memory (PROM), erasable programmable read-onlymemory (EPROM), electrically erasable PROM (EEPROM), registers, and soforth, including combinations thereof.

Data 2203 a and instructions 2205 a may be stored in the memory 2201.The instructions 2205 a may include one or more programs, routines,sub-routines, functions, procedures, etc. The instructions 2205 a mayinclude a single computer-readable statement or many computer-readablestatements. The instructions 2205 a may be executable by the processor2215 to implement one or more of the methods 200, 300, 1500, 1600, 1700,1800, 1900, 2000, 2100 that were described above. Executing theinstructions 2205 a may involve the use of the data 2203 a that isstored in the memory 2201. FIG. 22 shows some instructions 2205 b anddata 2203 b being loaded into the processor 2215.

The station 2206 may also include a transmitter 2211 and a receiver 2213to allow transmission and reception of signals between the station 2206and a remote location (e.g., an access point, base station or otherwireless communication device). The transmitter 2211 and receiver 2213may be collectively referred to as a transceiver 2209. An antenna 2207may be electrically coupled to the transceiver 2209. The station 2206may also include (not shown) multiple transmitters, multiple receivers,multiple transceivers and/or multiple antenna.

The various components of the station 2206 may be coupled together byone or more buses, which may include a power bus, a control signal bus,a status signal bus, a data bus, etc. For simplicity, the various busesare illustrated in FIG. 22 as a bus system 2217.

In some configurations, the station 2206 may further comprise a userinterface. The user interface may comprise a keypad, a microphone, aspeaker, and/or a display. The user interface may include any element orcomponent that conveys information to a user of the station 2206 and/orreceives input from the user.

FIG. 23 illustrates certain components that may be included within anaccess point 2304. The access point 104 described above may beimplemented in accordance with the access point 2304 described inconnection with FIG. 23. The access point 2304 includes a processor2333. The processor 2333 may be a general purpose single- or multi-chipmicroprocessor (e.g., an ARM), a special purpose microprocessor (e.g., adigital signal processor (DSP)), a programmable logic device (PLD), acontroller, state machine, gated logic, discrete hardware components,dedicated hardware finite state machines, a microcontroller, aprogrammable gate array, etc. The processor 2333 may be referred to as acentral processing unit (CPU). Although just a single processor 2333 isshown in the access point 2304 of FIG. 23, in an alternativeconfiguration, a combination of processors (e.g., an ARM and DSP) couldbe used.

The access point 2304 also includes memory 2319 in electroniccommunication with the processor 2333 (i.e., the processor 2333 can readinformation from and/or write information to the memory 2319). Thememory 2319 may be any electronic component capable of storingelectronic information. The memory 2319 may be random access memory(RAM), read-only memory (ROM), magnetic disk storage media, opticalstorage media, flash memory devices in RAM, on-board memory includedwith the processor, programmable read-only memory (PROM), erasableprogrammable read-only memory (EPROM), electrically erasable PROM(EEPROM), registers, and so forth, including combinations thereof.

Data 2321 a and instructions 2323 a may be stored in the memory 2319.The instructions 2323 a may include one or more programs, routines,sub-routines, functions, procedures, etc. The instructions 2323 a mayinclude a single computer-readable statement or many computer-readablestatements. The instructions 2323 a may be executable by the processor2333 to implement one or more of the methods 200, 1600, 1700, 1800, 2000described above. Executing the instructions 2323 a may involve the useof the data 2321 a that is stored in the memory 2319. FIG. 23 shows someinstructions 2323 b and data 2321 b being loaded into the processor2333.

The access point 2304 may also include a transmitter 2329 and a receiver2331 to allow transmission and reception of signals between the accesspoint 2304 and a remote location (e.g., a wireless communication device,a station, etc.). The transmitter 2329 and receiver 2331 may becollectively referred to as a transceiver 2327. An antenna 2325 may beelectrically coupled to the transceiver 2327. The access point 2304 mayalso include (not shown) multiple transmitters, multiple receivers,multiple transceivers and/or multiple antenna.

The various components of the access point 2304 may be coupled togetherby one or more buses, which may include a power bus, a control signalbus, a status signal bus, a data bus, etc. For simplicity, the variousbuses are illustrated in FIG. 23 as a bus system 2335.

In the above description, reference numbers may have been used inconnection with various terms. Where a term is used in connection with areference number, this may be meant to refer to a specific element thatis shown in one or more of the Figures. Where a term is used without areference number, this may be meant to refer generally to the termwithout limitation to any particular Figure.

The term “determining” encompasses a wide variety of actions and,therefore, “determining” can include calculating, computing, processing,deriving, investigating, looking up (e.g., looking up in a table, adatabase or another data structure), ascertaining and the like. Also,“determining” can include receiving (e.g., receiving information),accessing (e.g., accessing data in a memory) and the like. Also,“determining” can include resolving, selecting, choosing, establishingand the like.

The phrase “based on” does not mean “based only on,” unless expresslyspecified otherwise. In other words, the phrase “based on” describesboth “based only on” and “based at least on.”

As used herein, a phrase referring to “at least one of” a list of itemsrefers to any combination of those items, including single members. Asan example, “at least one of: a, b, or c” is intended to cover: a, b, c,a-b, a-c, b-c, and a-b-c.

The various operations of methods described above may be performed byany suitable means capable of performing the operations, such as varioushardware and/or software component(s), circuits, and/or module(s).Generally, any operations illustrated in the Figures may be performed bycorresponding functional means capable of performing the operations.

The various illustrative logical blocks, modules and circuits describedin connection with the present disclosure may be implemented orperformed with a general purpose processor, a digital signal processor(DSP), an application specific integrated circuit (ASIC), a fieldprogrammable gate array signal (FPGA) or other programmable logic device(PLD), discrete gate or transistor logic, discrete hardware componentsor any combination thereof designed to perform the functions describedherein. A general purpose processor may be a microprocessor or anycommercially available processor, controller, microcontroller or statemachine. A processor may also be implemented as a combination ofcomputing devices (e.g., a combination of a DSP and a microprocessor, aplurality of microprocessors, one or more microprocessors in conjunctionwith a DSP core, or any other such configuration).

In one or more aspects, the functions described may be implemented inhardware, software, firmware, or any combination thereof. If implementedin software, the functions may be stored on or transmitted over as oneor more instructions or code on a computer-readable medium.

The functions described herein may be stored as one or more instructionson a processor-readable or computer-readable medium. The term“computer-readable medium” refers to any available medium that can beaccessed by a computer or processor. By way of example, and notlimitation, such a medium may comprise RAM, ROM, EEPROM, flash memory,CD-ROM or other optical disk storage, magnetic disk storage or othermagnetic storage devices, or any other medium that can be used to storedesired program code in the form of instructions or data structures andthat can be accessed by a computer or processor. Disk and disc, as usedherein, includes compact disc (CD), laser disc, optical disc, digitalversatile disc (DVD), floppy disk and Blu-ray® disc where disks usuallyreproduce data magnetically, while discs reproduce data optically withlasers. It should be noted that a computer-readable medium may betangible and non-transitory. The term “computer-program product” refersto a computing device or processor in combination with code orinstructions (e.g., a “program”) that may be executed, processed orcomputed by the computing device or processor. As used herein, the term“code” may refer to software, instructions, code or data that is/areexecutable by a computing device or processor.

Software or instructions may also be transmitted over a transmissionmedium. For example, if the software is transmitted from a website,server, or other remote source using a coaxial cable, fiber optic cable,twisted pair, digital subscriber line (DSL), or wireless technologiessuch as infrared, radio, and microwave, then the coaxial cable, fiberoptic cable, twisted pair, DSL, or wireless technologies such asinfrared, radio, and microwave are included in the definition oftransmission medium.

The methods disclosed herein comprise one or more steps or actions forachieving the described method. The method steps and/or actions may beinterchanged with one another without departing from the scope of theclaims. In other words, unless a specific order of steps or actions isrequired for proper operation of the method that is being described, theorder and/or use of specific steps and/or actions may be modifiedwithout departing from the scope of the claims.

It is to be understood that the claims are not limited to the preciseconfiguration and components illustrated above. Various modifications,changes and variations may be made in the arrangement, operation anddetails of the systems, methods, and apparatus described herein withoutdeparting from the scope of the claims.

What is claimed is:
 1. A method for wireless communication by a station,comprising: preparing a power save polling (PS-POLL) request messagecomprising a token number, wherein the token number in the PS-POLLrequest message is the token number in one or more previous pagingmessages and is configured to indicate a correspondence between thePS-POLL request message and the one or more paging messages; andtransmitting the PS-POLL request message to an access point.
 2. A methodfor wireless communication by an access point, comprising: preparing aplurality of paging messages, wherein each of the plurality of pagingmessages is associated with at least one paging identifier of aplurality of paging identifiers and comprises a token number, whereineach of the plurality of paging identifiers is associated with at leastone station of a set of stations; transmitting at least one pagingmessage to the at least one station; receiving a power save polling(PS-POLL) request message from the at least one station, wherein thePS-POLL request message comprises the token number, wherein the tokennumber in the PS-POLL request message is the token number in one or moreprevious paging messages and is configured to identify the PS-POLLrequest message as corresponding to the one or more paging messages; andassociating the one or more paging messages with the PS-POLL requestmessage.
 3. A station configured for wireless communication, comprising:a processor; memory in electronic communication with the processor;instructions stored in the memory, the instructions being executable to:prepare a power save polling (PS-POLL) request message comprising atoken number, wherein the token number in the PS-POLL request message isthe token number in one or more previous paging messages and isconfigured to indicate a correspondence between the PS-POLL requestmessage and the one or more paging messages; and transmit the PS-POLLrequest message to an access point.
 4. An access point configured forwireless communication, comprising: a processor; memory in electroniccommunication with the processor; instructions stored in the memory, theinstructions being executable to: prepare a plurality of pagingmessages, wherein each of the plurality of paging messages is associatedwith at least one paging identifier of a plurality of paging identifiersand comprises a token number, wherein each of the plurality of pagingidentifiers is associated with at least one station of a set ofstations; transmit at least one paging message to the at least onestation; receive a power save polling (PS-POLL) request message from theat least one station, wherein the PS-POLL request message comprises thetoken number, wherein the token number in the PS-POLL request message isthe token number in one or more previous paging messages and isconfigured to identify the PS-POLL request message as corresponding tothe one or more paging messages; and associate the one or more pagingmessages with the PS-POLL request message.
 5. An apparatus configuredfor wireless communication, comprising: means for preparing a power savepolling (PS-POLL) request message comprising a token number, wherein thetoken number in the PS-POLL request message is the token number in oneor more previous paging messages and is configured to indicate acorrespondence between the PS-POLL request message and the one or morepaging messages; and means for transmitting the PS-POLL request messageto an access point.
 6. An apparatus configured for wirelesscommunication, comprising: means for preparing a plurality of pagingmessages, wherein each of the plurality of paging messages is associatedwith at least one paging identifier of a plurality of paging identifiersand comprises a token number, wherein each of the plurality of pagingidentifiers is associated with at least one station of a set ofstations; means for transmitting at least one paging message to the atleast one station; means for receiving a power save polling (PS-POLL)request message from the at least one station, wherein the PS-POLLrequest message comprises the token number, wherein the token number inthe PS-POLL request message is the token number in one or more previouspaging messages and is configured to identify the PS-POLL requestmessage as corresponding to the one or more paging messages; and meansfor associating the one or more paging messages with the PS-POLL requestmessage.
 7. A computer-program product for wireless communication, thecomputer-program product comprising a non-transitory computer-readablemedium having instructions thereon, the instructions being executable bya processor to cause a station to perform the steps of: preparing apower save polling (PS-POLL) request message comprising a token number,wherein the token number in the PS-POLL request message is the tokennumber in one or more previous paging messages and is configured toindicate a correspondence between the PS-POLL request message and theone or more paging messages; and transmitting the PS-POLL requestmessage to an access point.
 8. A computer-program product for wirelesscommunication, the computer-program product comprising a non-transitorycomputer-readable medium having instructions thereon, the instructionsbeing executable by a processor to cause an access point to perform thesteps of: preparing a plurality of paging messages, wherein each of theplurality of paging messages is associated with at least one pagingidentifier of a plurality of paging identifiers and comprises a tokennumber, wherein each of the plurality of paging identifiers isassociated with at least one station of a set of stations; transmittingat least one paging message to the at least one station; receiving apower save polling (PS-POLL) request message from the at least onestation, wherein the PS-POLL request message comprises the token number,wherein the token number in the PS-POLL request message corresponds tothe token number in one or more previous paging messages and isconfigured to identify the PS-POLL request message as corresponding tothe one or more paging messages; and associating the one or more pagingmessages with the PS-POLL request message.